Mastering The Technical Approach To The Scarf Bunionectomy

The European approach to the bunion commonly involves the scarf bunionectomy, much more so than here in the United States. Of the many bunion approaches, why should we bother adding another to the list? Those who utilize the scarf approach understand the stability, power of correction and utilitarian nature of this bunionectomy choice. I use the scarf as one of my go-to procedures for correcting mild to severe hallux abducto valgus.

   During my foot and ankle surgical fellowship in Columbus, Ohio, I was fortunate to spend time with a “traveling” surgeon offering his European expertise regarding the scarf bunionectomy. His influence was borne out of his training, his own surgical practice and the second edition of Forefoot Reconstruction by Louis-Samuel Barouk, MD.1 This is a well-written basis for approaching the common first ray deformity with the scarf. I have referenced it multiple times in my attempt to master the scarf bunionectomy and it has served me well.

   One should approach the scarf bunionectomy as a step-wise procedure.

   The chronological steps include:
1) Lateral release of the metatarso-sesamoidal phalangeal complex
2) Scarf first metatarsal osteotomy
3) Medial soft tissue tightening
4) Akin phalangeal osteotomy

Releasing The Metatarso-Sesamoidal Phalangeal Complex

The first step of the bunionectomy is the metatarso-sesamoidal phalangeal complex lateral release. Even in more mild cases, one still does this step to ensure appropriate balancing and lasting correction. There are two goals with the lateral release.

   1) Detaching the sesamoids from the first metatarsal head. The sesamoids are typically in the same relationship to the second metatarsal throughout the course of the deformity. By releasing the sesamoids from the first metatarsal head, the first metatarsal head, once cut, can shift back directly over the sesamoids.

   2) Avoiding overcorrection. This occurs by leaving the metatarsophalangeal collateral ligament uncut. This will allow correction yet prohibit the hallux from varus.

   Although one can perform the release from the medial aspect of the joint, I prefer the lateral intermetatarsal approach. This allows unmatched visualization of the anatomy. It also allows for access to the second metatarsal head, when necessary, through a shared incision.

   One would make the incision longitudinally in the intermetatarsal region. Finger or blunt dissect to the metatarso-sesamoidal phalangeal complex. Palpate the sesamoid and transect the sesamoidal suspensory ligament. This allows visualization of the superior surface of the sesamoid. The next move is to release the proximal insertional band off the proximal phalanx. This allows the hallux to derotate and removes the lateral directed tension. In mild cases, one can skip this step but I recommend this step for moderate and severe cases. This is typically all that is necessary to release the sesamoids and hallux sufficiently. It is important to leave the lateral collateral ligament intact to prevent hallux varus. Lastly, if the sesamoid is arthritic and adherent, the surgeon should remove it.

Key Pearls On Performing The Scarf Osteotomy

The second step is the osteotomy itself. Making two interlocking chevron cuts increases the scarf’s stability. The shift can correct for the intermetatarsal angle and one can rotate in several directions, allowing versatility. The surgeon can also correct for shortening and lengthening with the osteotomy.

   The blood supply to the first metatarsal head primarily enters from the plantar neck region and to a secondary degree dorsally at the capsular area. The scarf osteotomy respects both of these very nicely. The approach is a medial longitudinal incision, which the surgeon takes down to bone along nearly the entire first metatarsal. Incise the capsule with a lenticular approach. No vertical capsulorrhaphy is necessary. Reflect the abductor hallucis muscle belly plantarly on the proximal aspect for saw blade excursion. Similarly, reflect the area dorsally and proximal to the capsule insertion, protecting the blood supply and offering a clear visual field for the osteotomy.

   Perform a minimal medial eminence resection to allow for ease with the scarf cut. Make the longitudinal cut first, determining the angles based on deformity correction needs. Make the longitudinal cut from the metaphyseal region to the metaphyseal region. Make sure the cut remains parallel or nearly so to the ground, not the shaft.

   The cut should start superior to the midline and traverse with a plantar orientation to allow plantar translation as one performs the shift. This is beneficial in the majority of cases to allow the medial column an advantage to once again bear the load it was intended to bear and often obviates the need for an adjunctive Weil osteotomy. Then perform dorsal, distal and proximal plantar cuts parallel to each other. One will only need to cut 2 to 3 mm of bone. This reduces the stress riser and if the metatarsal is shortened, it will not be elevated in the process.

   If one desires less than 3 mm of length correction, changing the axis of the proximal and distal cuts is all that is necessary. The cuts must remain parallel to allow length change to occur and remain stable. If more than 3 mm of length, usually shortening, is necessary, simply remove a piece of bone to the amount of correction desired from both the proximal and distal ends.

What You Should Know About Shifting The Metatarsal

Now we are ready to shift. This requires a pushing-pulling maneuver. The shift can be substantial, up to three-quarters of the available shelf. Utilize a bone clamp or temporary K-wires to assess the shift. Loading the first ray should show a desirable intermetatarsal correction and a balanced hallux. If not, remove temporary fixation and adjust the shift. If a decrease in range of motion is present, further shortening should correct for this by decreasing tension on the flexor hallucis brevis tendon primarily.

   Perform fixation with either two parallel dorsal to plantar screws or one dorsal to plantar screw proximally and one from dorsal and angling 45 degrees toward the metatarsal head. This second orientation decreases troughing and allows compression across the proximal and distal cuts. The troughing is minimal when one extends the longitudinal cut from the metaphyseal bone distally to the metaphyseal bone proximally. The long arm also gives power to the corrective ability and a large surface area for screw placement and bone healing. Resection of any overhanging medial eminence completes the bony work.

   Then perform the capsulorrhaphy medially by bringing the longitudinal (lenticular) capsule together. This secures the sesamoids in position beneath the corrected metatarsal head. The vertical capsulorrhaphy is not necessary as this lateral release and the bony correction have reduced the deformity. Tightening the capsule in the vertical plane reduces postoperative range of motion but surgeons can avoid this. Plantarflexing the hallux during the repair and throwing one solid suture at the point of rotation is the key to capsular closure.

   If the hallux still has an abductory component, an Akin osteotomy can achieve desired outcomes. One can perform the Akin by extending the medial incision and choosing either a transverse or oblique osteotomy. Akin fixation includes screws, staples or wire.

In Conclusion

The patient can bear weight immediately after the procedure in a post-op shoe or boot. If swelling allows, a return to regular shoegear at four weeks is expected. I have been satisfied both clinically and radiographically approaching bunions with this scarf technique. I feel the procedure is reproducible, versatile and a solid option for correcting bunions.

   Dr. Bussewitz is a fellowship-trained foot and ankle surgeon who is currently in private practice in Iowa City, Iowa.

Reference
1. Barouk LS. Forefoot Reconstruction, second edition, Springer, New York, 2005. 


   For further reading, see the DPM Blog “What I Look For In A Bunionectomy Procedure” at https://tinyurl.com/9w4gbfu or “Mastering The Scarf Bunionectomy” in the January 2003 issue of Podiatry Today.