Point-Counterpoint: Should The Lapidus Replace The Closing Base Wedge Osteotomy?

Yes, this author says the Lapidus facilitates better first ray stability, allows more intraoperative flexibility and is an easier procedure to perform and fixate. By Babak Baravarian, DPM As the field of foot and ankle surgery has evolved, there has been a dramatic shift in hallux abducto valgus surgery. Currently, the primary treatment goals are ensuring proper alignment of the first metatarsal in both the sagittal, frontal and transverse planes, and facilitating the best long-term outcome. When it comes to realignment of the first ray in all three planes and minimizing the chance of recurrence, the Lapidus bunionectomy is the ideal surgical procedure. There are several reasons for using a Lapidus bunionectomy in comparison to a closing base wedge procedure. Employing the Lapidus bunionectomy enables one to achieve a greater level of first ray stability and allows for unlimited correction of the first ray in all three planes of motion with the possibility of intraoperative correction of alignment. The Lapidus bunionectomy virtually prevents the possibility of the bunion deformity from reoccurring. The Lapidus is also far simpler to perform and fixate in comparison to the closing base wedge procedure. As noted by Morton in his studies, the first ray lacks stability when one compares it to the lateral rays. This lack of stability allows for medial shift of the ray and hallux valgus formation. While researchers have shown some association with the cause of hallux valgus being related to the position of the distal articular cartilage of the first metatarsal and tendon imbalance of the great toe, the most common cause of deformity is related to the laxity of the first metatarsocunieform joint. With this laxity, there is a medial shift and relative elevatus of the first metatarsal as well as a medial shift of the great toe. Too often, this underlying instability is missed as an underlying cause and symptom of hallux valgus deformity. Callus formation or pain plantar to the second metatarsal, thickening of the second metatarsal shaft and dorsal spurring of the first metatarsal with exostosis of the first metatarsocunieform joint are all signs of possible first ray laxity. The single greatest positive factor for employing the Lapidus procedure is the added stability one can provide to the midfoot and medial column. This allows for better function of the peroneus longus tendon and retrograde stability of the rearfoot complex with a better shift of weight from the rearfoot to forefoot. How The Lapidus Allows More Intraoperative Flexibility A closing base wedge is a very difficult procedure to comprehend conceptually. It is difficult to perform well consistently, considering the triplane correction required for proper hallux valgus correction. While it is fairly easy to perform a wedge procedure and correct the intermetatarsal angle, it is far more difficult to correctly reduce the intermetatarsal angle, plantarflex the first metatarsal and correct possible frontal plane rotation of the ray with a wedge removal of bone. This subsequently results in a possible elevated ray, overcorrected angle and poor alignment. By performing the Lapidus with curettage and realignment, one can reduce the intermetatarsal angle, shift the first metatarsal plantar to correct elevatus and rotate the first metatarsal to correct frontal deformity. Although it is slightly more difficult to facilitate a frontal rotation and plantar shift with wedge correction Lapidus procedures, it is still possible. The Lapidus is also an excellent procedure as one can fine tune the correction under fluoroscopy, limiting the chance of over- or undercorrection prior to placing the fixation. Once one has performed a closing wedge osteotomy of the first metatarsal, it is very difficult to correct the alignment without breaking the hinge and/or further osteotomy of the bone. Addressing The Issue Of Large Intermetatarsal Angles Although one can correct a large intermetatarsal (IM) angle with a closing base wedge, if a closing wedge is required for correction of a large IM angle, there must be a severe hallux valgus. This may be due to the instability of the medial column. If this is the case, there may be a high chance of recurrence of the deformity in a young or very active person due to the extreme loads placed on the medial column. While a closing base wedge can realign the ray and correct stability issues, it is not as strong or definitive a procedure for stabilization and realignment as the Lapidus. When one performs fusion of the first metatarsocuneiform joint, there is virtually no chance of a true hallux valgus reoccurrence. Although there can be a return of a lateral hallux shift from poor tendon balance, the only way the first ray can shift medially is if there is instability between the cuneiform joints. The reduced potential for recurrence leads to a great deal of patient satisfaction and since the two procedures require virtually the same postoperative nonweightbearing course, there is no reason to perform a closing base wedge procedure in the face of instability that one often finds with large IM angles. Why The Lapidus Is Simpler To Perform And Fixate While the Lapidus procedure is intimidating to some, it is far simpler to perform and fixate compared to a closing base wedge procedure. I use a curettage technique without power instrumentation (with the exception of fenestrating the subchondral bone with a wire or small drill bit). This is simple to perform and the joint distractor facilitates good joint access. After preparing the joint, I open the first metatarsophalangeal joint, resect the medial eminence and perform a collateral and lateral release. I try to limit dissection of the first metatarsophalangeal joint to prevent scarring and stiffness. I then position the toe and hold it while I run my temporary fixation in the fusion site. Position is checked during fixation under fluoroscopy. Furthermore, if there is an issue with fixation failure, I can switch my fixation to a dorsal medial compression plate or an external uniplane fixator with no severe loss of stability or compression at the fusion site. I can also bone graft the site in the event of a short metatarsal or revision case. To perform a closing base wedge well, the wedge must be correct and accurate in all three planes. There is very limited error in judgment possible. The location of the osteotomy must exit at the proper site in order to allow proper closure of the wedge without fracture. The wedge also must be large enough to accept two points of stable fixation without fracturing of the wedge at the time of closure and without a stress riser between the two screw holes. If there is a fixation failure, the only true fixation option is crossed wires with poor compression. In Conclusion In my opinion, the closing base wedge is a difficult and outdated procedure that does not treat the true underlying cause of hallux valgus, and does not tend to increase the stability of the medial column as well as a Lapidus procedure. Although the Lapidus procedure is challenging at first, when one masters it, the Lapidus is the most dramatic and powerful procedure in the stabilization and correction of hallux valgus, metatarsal primus elevatus and medial column instability. Dr. Baravarian is an Assistant Clinical Professor at the UCLA School of Medicine. He is also the Co-Director of the Foot and Ankle Institute of Santa Monica, Ca. His e-mail address is bbaravarian@mednet.ucla.edu. No, the authors emphasize the key benefit of preserving motion with the closing base wedge osteotomy (CBWO). They also defuse perceptions about metatarsal length shortening and union rates with the CBWO. By Donald R. Green, DPM, and Peter Kim, DPM, MS Both the closing base wedge osteotomy (CBWO) and the Lapidus procedures have been shown to be effective over the years. Both procedures have also proven to be moderately difficult technically. If there is arthrosis or painful motion at the first metatarsocuneiform joint, the Lapidus is the more appropriate procedure to eliminate the pain. If there is dislocation (significant subluxation) of the first metatarsocuneiform joint, once again the fusion of the joint is the most appropriate stabilizing procedure. However, it is generally accepted there is less shortening, quicker healing and less postoperative disability with the CBWO versus the Lapidus procedure. The most significant difference between the two is preservation of motion as the CBWO allows for a more biomechanically sound postoperative gait pattern. Proximal first metatarsal osteotomies are indicated for the surgical correction of moderate to severe hallux abducto valgus (HAV) deformities because of their powerful angular corrective nature. The CBWO is one such procedure that has been a reliable mainstay over the years and is amenable to several stable fixation techniques for predictable results. When neck osteotomies are contraindicated or in cases in which there is a large intermetatarsal (IM) angle, employing a basilar approach such as the oblique CBWO can effectively correct the deformity while facilitating joint preservation to all segments distal and proximal to the surgical site. The classic transverse closing wedge osteotomy through the base of the first metatarsal was initially described by Loison in 1901, and was performed again in 1903 by Balacescu, who resected a wedge of bone from the medial cuneiform in addition.1,2 In 1919, Juvara noted that the oblique CBWO was an important enhancement.3 When the base wedge osteotomy became more widely used around 1970, complications such as first metatarsal elevatus, shortening, failed fixation and delayed bone healing led many to believe that less than satisfactory results were inherent to the procedure. However, as a result of improved surgical technique, appropriate stable fixation and sufficient postoperative non-weightbearing protection, subsequent outcomes showed the CBWO to be a powerful tool in the arsenal against HAV.4 The Podiatry Institute introduced the contemporary version in 1977 as an oblique wedge designed for fixation by two 2.7-mm cortical screws as opposed to K-wire technique with the proximal osteotomy oriented 45 degrees from the longitudinal metatarsal axis.5 The obliquity of the osteotomy yields a longer cut, effectively reducing the amount of bone one removes from the wedge. This facilitates less metatarsal shortening as opposed to the classic transverse osteotomy. Furthermore, this procedure also lends itself to the hinge axis concept for accurate triplanar positioning of the metatarsal upon reduction of the angular deformity.4,6,7 Recognizing The Adjunctive Value Of The CBWO In Addressing Severe IM Angles This CBWO procedure remains a very useful adjunct in the comprehensive approach to correct surgically HAV deformities with severe IM angle deviations or IM angles with increased metatarsus adductus angles (MAA). It offers a true reduction of the IM angle without sacrificing significant bone loss. Recently, Lutonsky and Sponer reported that they corrected the IM angle by 10 degrees within a group of 12 adolescent feet.8 Seiberg, et. al., found an average IM angle reduction of 12.1 degrees at least six months postoperatively.9 Pontious, et. al., reported that the average IM angle correction on follow-up decreased from a pre-op measurement of 13.21 degrees to a post-op measurement of 4.29 degrees.10 Ruch’s subgroup of 150 patients who remained nonweightbearing for at least four weeks had an average IM angle reduction of 12 degrees.11 Schuberth, et. al., noted greater than 8 degrees of relative reduction, while Nigro, et. al., obtained greater than 6 degrees of correction.6,12 Static laboratory model studies have also validated the efficacy of the transverse plane correction using the oblique CBWO. While Nyska, et. al., recently obtained only 5 degrees (SD = 3.8 degrees) of reduction (their oblique CBWO construct was not pre-reduced with bone clamps), models used by Fillinger, et. al., were reduced by 12 degrees.13,14 Addressing The Issue Of Metatarsal Length Shortening Research has not supported the notion of excessive shortening when the CBWO is well controlled. In fact, the postoperative metatarsal protrusion distance is on par with “safer” distal osteotomies. It is even less when one compares it to the postoperative metatarsal protrusion surgeons may see with the Lapidus arthrodesis, a procedure that requires you to resect and/or curet biarticular cartilage and portions of subchondral bone. With a 10 degree wedge resection angle, Banks, et. al., found that shortening was minimized to 1.7 mm while Nyska, et. al., noted a 2.0 mm shortening among their static models.13,15 Higgins, et. al., found shortening averaged 1.3 to 2.3 mm depending on fixation technique.16 Seiberg, et. al., observed that the metatarsal protrusion distance was shortened by 2.9 mm after a minimum of six months post-op, although it was only 2.6 mm immediately postoperative.9 On the other hand, the Lapidus arthrodesis yields more first ray shortening. When one employs a wedge resection, an average of 5 mm shortening can occur.17 Other studies have concurred with findings ranging from 4.7 to 7.5 mm.18-20 Even with subchondral bone preservation, shortening can still be pronounced.19 Comparing Reported Union Rates Between The Two Procedures Although there is a paucity of recent data for bone union rates using the oblique CBWO, delayed and non-unions are far less prevalent than historically perceived. In 1982, Ruch found that among 50 cases that involved six weeks of postoperative management with a nonweightbearing short leg cast, only one case (2 percent) ultimately developed failure of fixation while another (2 percent) showed external callus formation.11 In Polansky’s small study in 1985 using Herbert screw fixation, no bone healing failure was observed.21 In 1994, Seiberg, et. al., reported no incidents of delayed or non-unions among 31 oblique CBWO procedures.9 Pontious, et. al., reviewed adolescent HAV cases, 35 of which included the CBWO. They found no complications of osteotomy healing.10 In 1996, Higgins, et. al., reviewed 33 consecutive CBWO procedures and also reported stable bone healing and no failures.16 However, union rates for the Lapidus can be more problematic. Although lesser nonunion rates have been reported (3.3 percent by Grace, et. al., and 5.3 percent by Patel, et. al.), bone healing complications can be high.22,23 Metzdorf and Strehle observed a nonunion rate of 8.8 percent; Sangeorzan and Hansen reported 10 percent; Catanzariti, et. al., noted 10.6 percent; and Coetzee, et. al., cited 11.5 percent.17,18,24,25 Furthermore, Saffo, McInnes and Myerson all found 12 percent nonunion rates.19,20,26 What About Postoperative Elevatus? While postoperative dorsal translocation of the distal segment is an inherent risk to the CBWO, it is not any more than with other proximally based osteotomies. Indeed, the proper use of the hinge axis concept can preserve or even reverse the first metatarsal head sagittal plane position. In 1984, Schuberth, et. al., found that nearly 94 percent of first metatarsals were elevated among 159 procedures studied.6 In fact, the average elevation was nearly 6.7 degrees, given that the treatment varied with regards to laterality, fixation technique, immediate weightbearing and patient age. (Not surprisingly, shortening was also the greatest in this study due in large part to the elevatus which results in a radiographic artifact of apparent shortening.) However, one sees minimized postoperative elevatus in studies that have taken these factors into account. Higgins, et. al., reported 0.8 degrees of elevatus using double Kirschner wire fixation while Seiberg, et. al., found 1.1 degrees using either cortical or cancellous screw fixation.9,16 In both studies, researchers emphasized strict non-weightbearing for at least six weeks. Pertinent Points On Postoperative Care The inherent proximal nature of the osteotomy imposes a higher dorsiflexory moment arm that one must neutralize. In adherence to basic tenets of AO fixation techniques, it is generally agreed that early weightbearing in the postoperative phase is contraindicated. Despite the six-week inconvenience of non-weightbearing, subjective patient satisfaction rates have remained high. Studies showing excessive shortening, elevatus, robust callus formation or failed unions have been correlated to premature weightbearing. A knee walker with 5-inch wheels has been the device of choice for some patients who find ambulating with crutches difficult.27 The Roll-A-Bout is also an excellent alternative to help maintain non-weightbearing.28 Post-op care for the Lapidus can be slightly longer. Some have cited the upper end of the non-weightbearing period for the Lapidus as being between eight and 10 weeks.18,29-31 If one employs a bone graft, the non-weightbearing period may even require 12 weeks.32 Preserving Motion: Understanding A Key Benefit Of The CBWO One of the less touted but more obvious advantages to this basilar osteotomy is that it allows for continued natural ROM throughout the rest of the joints in the foot. Tensegrity is a system based on the naturally occurring, self-generating truss. It is an optimized, low-energy omnidirectional hierarchical construct. There is a cabling effect, an example of which is demonstrated by the cable cranes one would see in high-rise building construction projects. Changing one part affects the rest. Forces tend to return to their original state. With biotensegrity, the foot becomes part of an integrated truss system. As in all truss constructs, there are only tension and compression elements. There are no levers or bending moments nor is there any torque at the joints.33 This makes for a mechanically efficient system that stores and returns energy with smooth motion in an efficient gait pattern. Muscles develop tension on the fascia, providing protection, energy return and smooth motion. Arthrodesis leads to “disintegration of gait” with increased energy consumption, decreased gait speed and increased pressure on other joints. One would see a good example of this with ankle arthrodesis.34 Although fusion of the first metatarsal cuneiform joint will not have as dramatic effect as fusion of the ankle joint, is there any doubt that there will be some gait disintegration and new stresses placed on other joints? Arthrodesing procedures create circumstances that are consistent with the aging process. Decreasing tension with loss of flexibility and mobility increases stiffness. There is decreased energy efficiency and increased demands on other joints.35 Recently, Lakin, et. al., reported the quantitative significance of contact mechanics across the Lisfranc complex.36 They eloquently demonstrated how each metatarsal cuneiform joint is significantly involved in regulating pressures and redirecting forces in response to leg bone axial compressive loads. Dananberg has lectured extensively on the relationship of back-connected pathology related to decreased motion of the first metatarsophalangeal motion, and decreased motion of the first ray.37 First ray plantarflexion is necessary for normal gliding motion of the first metatarsophalangeal joint. Mobility of the first ray allows increase range of motion of the first metatarsophalangeal joint.38 Therefore, one should exercise caution when contemplating use of the Lapidus procedure. Final Notes Both the oblique CBWO and the Lapidus procedures are effective in correcting large IM angles. Both are moderately difficult to perform. Lapidus is the procedure of choice when there is metatarsocuneiform joint arthritis, painful motion or dislocation. The closing base wedge osteotomy is preferred in other instances because there is less shortening of the first metatarsal, better healing and less postoperative disability. However, the most important advantage of the CBWO is preservation of motion across the first ray. One should be cautious in regard to the Lapidus procedure. It’s important to remember that arthrodesing procedures create circumstances consistent with the aging process and stiffness. Some gait disintegration and abnormal mechanotransduction to surrounding joints can lead to new joint pathologies and inefficiency in gait. Dr. Green is the Director of Podiatric Surgical Residency at the Scripps Mercy Medical Center in San Diego. He is a Clinical Professor at the California School of Podiatric Medicine at Samuel Merritt College and is a Fellow of the American College of Foot and Ankle Surgeons. Dr. Green is also on the faculty of the Podiatry Institute and has a private practice in San Diego. Dr. Kim is a recent graduate of the Temple University School of Podiatric Medicine and is a first-year PSR-36 resident at the Scripps Mercy Medical Center in San Diego.
 

References:

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