Pertinent Insights On Proximal Bunionectomies

In nearly a century of existence, the Lapidus bunionectomy has evolved along with advances in fixation hardware and technique. Accordingly, these authors discuss indications, surgical technique and the scientific evidence behind using this procedure for proximal bunionectomies.

Multiple options exist for the correction of severe bunion deformities requiring proximal procedures. Corrective procedures that have well documented success include the closing and opening wedge osteotomies, double metatarsal osteotomies and the Lapidus arthrodesis.

   The opening base wedge osteotomy originally required an interpositional graft with no fixation. While surgeons were able to successfully reduce the large intermetatarsal angle without compromising length, the lack of fixation leads to multiple complications. Specifically, complications include the propensity of the lateral hinge to break, causing the distal fragment to move in any of the three planes of the foot. Due to the advent and improvement in internal fixation, surgeons can successfully execute and consistently reproduce these procedures without the increased concern of correction failure, thus decreasing healing time and allowing patients to bear weight sooner.

   In their study of 66 patients with closing wedge osteotomies, Nedopil and colleagues applied a plate with five screws for fixation and initiated weightbearing to tolerance at two days post-op.1 After an average of 52 months’ follow-up, only one of the 86 feet developed a nonunion.

   Much can be said for these advancements and their benefits regardless of the proximal procedure one chooses. As with all elective surgical procedures, each comes with its own unique challenges, advantages and disadvantages. Selection of the proper procedure is imperative to the overall goal of the correction, pain reduction and the patient’s level of satisfaction. Proper evaluation of the intermetatarsal angle, metatarsal length, hypermobilty, sesamoid position and hallux abductus angle guide the procedural selection process. Additionally, secondary pathology such as lesser metatarsalgia and second metatarsophalangeal joint (MPJ) overload dictate the procedure choice.

What You Should Know About The Evolution Of The Lapidus Procedure

Introduced nearly 100 years ago, the Lapidus arthrodesis continues to be an excellent treatment option for hallux valgus deformities. Its power lies in its ability to simultaneously correct deforming planes such as adduction, plantarflexion, rotation and stability of the medial column as well as long-term maintenance of correction.

   Haas and co-workers performed a study of 57 feet comparing the closing base wedge osteotomy with the Lapidus arthrodesis.2 The authors demonstrated that the closing base wedge osteotomy had a loss of intermetarsal correction of 2.55 degrees from preoperative films to late postoperative films in comparison to the Lapidus, which only lost 1.08 degrees of intermetatarsal correction. When surgeons ensure proper fixation with a stable construct, they may achieve early weightbearing and have decreased concern for nonunion.

   Originally, surgeons performed the procedure much as they do today with the exception of fixation. Early fixation of bone was limited to heavy suture until later developments allowed for internal screw fixation. From the inception of the Lapidus procedure through its evolution to today, much advancement has occurred through research and development of internal fixation and knowledge gained in regard to bone healing.
Traditionally, the Lapidus procedure was reserved for large intermetatarsal angle bunion deformities. Today, surgeons can also use the Lapidus procedure to successfully treat recurrent hallux valgus, a long first metatarsal with mild hallux abducto valgus and hypermobility of the first ray.

   For overall successful fusion, pain relief and corrective achievement, stable fixation is imperative. Surgeons have introduced multiple modifications of the Lapidus. Namely, changes in joint preparation and internal fixation constructs have increased the overall success rates and the utilitarian nature of the procedure. Traditional fixation methods include two-screw fixation across the first metatarsocuneiform joint. Some surgeons place an additional screw from the first metatarsal into the second metatarsal or from the first metatarsal to the medial cuneiform.

   With the advent of locking plate technology, surgeons commonly use plate fixation to augment traditional fixation constructs. The addition of the plate with screw fixation can allow for early weightbearing with a low risk of postoperative complications such as nonunion.

   A study by Saxena and colleagues focused on 40 patients who underwent the Lapidus arthodesis.3 Surgeons fixated 19 patients with two cross lag screws and 21 patients with a locking plate and a plantar lag screw. The locking plate with the plantar lag screw group could bear full weight at four weeks. The crossed lag screw group followed the traditional postoperative course of six weeks of non-weightbearing. The results showed no significant difference between the two groups postoperatively.

   We utilize the Lapidus as a standard proximal bunion procedure due to increased stability and correction of hallux abducto valgus and hypermobility with a high degree of predictability.

A Guide To Current Indications For The Lapidus Procedure

The indications for the Lapidus procedure continue to gain popularity secondary to the long-term and reproducible results of the operative treatment. Current indications for the Lapidus procedure include:

• correction of moderate to severe hallux abducto valgus recalcitrant to conservative treatment;

• a symptomatic elevated first ray;

• a hypermobile first ray with clinically identifiable transfer metatarsalgia resulting in second metatarsal overload syndromes;

• adolescent hallux abducto valgus deformity with associated hypermobility or generalized ligamentous laxity;

• deformity of the first metatarsocuneiform joint secondary to degenerative joint disease;

• other forefoot deformities resulting in instability of the medial column, such as splay foot and metatarsus adductus; and

• a salvage procedure for a previously failed bunion correction.

   Definite contraindications for this procedure include patients with open growth plates and active infection. Relative contraindications may include an excessively shortened first ray or when the patient has severe degenerative joint disease of the first MPJ. The literature has not explored the results of combined arthrodesis of the first MPJ and tarsometatarsal joint.4

Pertinent Insights On Surgical Technique

Based on our experience, we would like to offer a few pertinent points to ensure appropriate joint preparation, proper correction and stable fixation with the Lapidus arthrodesis.

   First, ensure the patient is in a supine position on the operating table. Typically, one places a small bump under the ipsilateral hip to slightly internally rotate the leg until the foot is in the appropriate anatomical plane. Place a pneumatic tourniquet around the ankle or thigh, depending on the type of anesthesia and whether one is addressing associated reduction of an equinus deformity. Make an incision from the base of the proximal phalanx medial to the extensor hallucis longus, extending proximally to the lateral aspect of the medial cuneiform. Take care to identify and retract the medial dorsal cutaneous nerve.

   Gain access to the metatarsocuneiform joint by performing a linear capsulotomy, creating a dorsal lateral and plantar medial flap. Employing a Freer elevator at the joint line facilitates identification of the periosteal/capsular layer. Start dissection at the joint line, extend it proximally and then distally. Take particular care to identify and avoid damaging the neurovascular bundle and perforating artery as well as the second metatarsal medial cuneiform ligament (Lisfranc ligament). It is also important to avoid cutting the tibialis anterior tendon medially at its insertion.

   The crucial step is the denudation of the adjacent articular surfaces at the first metatarsocuneiform joint. We prefer to use curettage and an osteotome technique for preparation of the fusion site. Use saw resection for “feathering” of the subchondral bone ends. Also, in regard to severe deformities, one can utilize planal resection with a saw for correction and alignment. Take care with this technique as shortening and dorsiflexion can easily occur, and lead to a poor result. A lamina spreader or Hintermann retractor can assist with joint exposure. Take care to remove all cartilage dorsal, plantar, distal and proximal in equal amounts. Due to the shape of the metatarsal and cuneiform, there is a propensity to take more bone dorsally than plantarly, causing distal elevation and dorsiflexion of the first ray.

   Once subchondral bone is exposed, it is imperative to break through the subchondral plate. Fenestrate the subchondral plate with either a 2.0 mm drill or 0.62 K-wire until bleeding bone is visible. It is our preference to use the 2.0 mm drill to decrease thermal necrosis and retain the bone from the drill bit to use as a bone graft. Oftentimes, one can resect the lateral eminence of the base of the first metatarsal to prevent abutting the second metatarsal during reduction.

   Before reducing the deformity, perform a distal metatarsophalangeal joint capsulotomy in the dorsal medial MPJ capsule. We typically delay resection of the dorsal medial eminence until the last step of the surgery. This discourages staking of the metatarsal head and the complication of hallux varus. Surgeons may perform a lateral release when indicated.

   Reduce the first intermetatarsal angle manually or with a large reduction clamp situated on the medial aspect of the first metatarsal and the lateral aspect of the second metatarsal. Then perform dorsiflexion of the first MPJ to enable the windlass mechanism to plantarflex the first ray. Employ temporary fixation and confirm reduction of the deformity using direct visualization and image intensification fluoroscopy.

   At this point, place a wire across the fusion site from the dorsal midshaft of the metatarsal to the plantar base of the medial cuneiform. In the opposing manner, place a wire from the dorsal medial cuneiform to the plantar lateral base of the first metatarsal. Employ a 3.5 or 4.0 mm cannulated lag screw across the fusion site. Alternatively, one can place fully threaded cortical lag screws in a similar fashion.

   After placing the screws, evaluate the foot for any intercuneiform/intermetatarsal instability. Surgeons commonly utilize a third screw, oriented from the proximal shaft of the first metatarsal to the base of the second metatarsal, to further stabilize the construct.

   An adjunct to the procedure is the use of locking plate technology in addition to compression screws. This incorporates the additional compression needed to facilitate bony ankylosis with the stability of a locking plate construct. After obtaining appropriate reduction and position of the fusion site, fashion a locking plate to the dorsal medial aspect of the fusion site. One may employ a combination of locking and non-locking screws to ensure a strong plate to bone interface without prominence.

   Finally, direct attention distal to the first MPJ, where resection of the dorsal medial eminence may be necessary to complete the procedure. Then close the incision in standard layered fashion. Dress the area and place the patient in a splint to facilitate initial non-weightbearing. Our postoperative course is protected partial weightbearing at four weeks, full weightbearing at six weeks in a controlled ankle motion (CAM) boot and conversion to a walking shoe at eight weeks.

A Closer Look At The Evidence

The popularity of the Lapidus procedure is highlighted by its ability to correct severe hallux abducto valgus and multi-planar instability. Although researchers first described this procedure many decades ago, the vast majority of outcome-based reports have been presented in the last 10 years.

   Cohen and colleagues compared an isolated locking plate technique to isolated cross screw fixation and found the latter to be a superior construct.5 However, the authors did not investigate the combination of lag screw with locking plate fixation.

   Scranton and co-workers evaluated the load to failure comparing single compression screw with a locking plate to a crossed screw configuration.6 In this cadaveric study, a higher load to failure rate occurred in the locking plate group.

   Sorensen and colleagues took their report further, looking at fusion rates and time to fusion for their cohort.7 Patients underwent Lapidus fusion using a single lag screw and locking plate construct. The study authors found the average fusion time was 6.95 weeks with no delayed unions or nonunions in their patient population. Time to weightbearing was two weeks for all patients. The authors concluded that the stability of the lag screw with a medial locking plate construct allows for early weightbearing with no reduction in fusion rates.7

In Summary

The benefit of the Lapidus procedure is evident and for proximal bunion deformities, we use it exclusively. Surgeons have made important advances with this procedure through consistent study and evaluation. These efforts have brought to light the complications and pitfalls of the procedure but most importantly, they have shown consistent and valid data to remedy these complications through further surgical advancements. Lastly, advancements in internal fixation paired with the evidence on stable constructs have given surgeons the confidence to advance their patients’ postoperative care more aggressively than in days past.

   We recommend the following pearls. Employ the curettage technique with minimal bone resection to reduce shortening and dorsiflexion. Since the Lapidus procedure allows for correction in multiple planes, reserve the resection of the medial eminence for final osseous correction. Employ the “third” screw technique, medial plate fixation or intermediate cuneiform fixation to reduce first and second ray instability, and strengthen the construct.

   Dr. Reeves is an Attending Physician with the Florida Hospital East Orlando Residency Training Program. He is a Fellow of the American College of Foot and Ankle Surgeons, and a Diplomate of the American Board of Podiatric Surgery.

   Dr. Shane is an Attending Physician with the Florida Hospital East Orlando Residency Training Program. She is a Fellow of the American College of Foot and Ankle Surgeons, and a Diplomate of the American Board of Podiatric Surgery.

   Dr. Thurston is a second-year resident at Florida Hospital in Orlando.

   Dr. Wobst is a second-year resident at Florida Hospital in Orlando.

References
1. Nedopil A, Maximilian R, Gradinger R, Schuster T, Bracker W. Closed wedge osteotomy in 66 patients for the treatment of moderate to severe hallux valgus. Foot Ankle Surg. 2010; 16(1):9-14.
2. Haas Z, Hamilton G, Sundstrom D, Ford L. Maintenance of correction of first metatarsal closing base wedge osteotomies versus modified Lapidus arthrodesis for moderate to severe hallux valgus deformity. J Foot Ankle Surg. 2007; 46(5):358-365.
3. Saxena A, Nguyen A, Nelsen E. Lapidus bunionectomy: early evaluation of crossed lag screws versus locking plate with plantar lag screw. J Foot Ankle Surg. 2009; 48(2):170-179.
4. Toolan, BC. Surgical strategies: the Lapidus procedure. Foot Ankle Int. 2007; 28(10):1108–1114.
5. Cohen DA, Parks BG, Schon LC. Screw fixation compared to H-locking plate fixation for first metatarsocuneiform arthrodesis: a biomechanical study. Foot Ankle Int. 2005; 26(11):984–989.
6. Scranton PE, Coetzee JC, Carreira D. Arthrodesis of the first metatarsocuneiform joint: a comparative study of fixation methods. Foot Ankle Int. 2009; 30(4):341–345.
7. Sorensen MD, Hyer CF, Berlet GC. Results of Lapidus arthrodesis and locked plating with early weight bearing. Foot Ankle Specialist. 2009; 2(5):227–33.