indications and technique of the weil osteotomy - The Podiatry Institute

C H A P T E R 3INDICATIONS AND TECHNIQUE OF THEWEIL OSTEOTOMYRichard J. Zirm, DPMINTRODUCTIONThe Weil osteotomy has become a popular technique forthe surgical treatment of resistant lesser metatarsalgia.Metatarsalgia is a vague, catch-all term that representstenderness and pain in the plantar forefoot. Metatarsalgiacan develop from osseous, soft tissue, neurologic, vascular,or dermal etiologies. It is a somewhat common presentingcomplaint that can interfere with normal ambulation,work, fitness, and recreation.Physical evaluation of the patient can determine theunderlying etiology. Metatarsalgia can be subdivided intoprimary versus secondary causes as well as structural versusfunctional causes (Table 1). A different combination of theseunderlying factors can characterize symptoms that occurduring the stance phase of gait versus the propulsive phase.The surgical treatment of metatarsalgia has beensomewhat controversial. Ideally, conservative treatmentshould be exhausted before surgical options are considered.To date, more than 25 different lesser metatarsalosteotomies have been described. Weil described anosteotomy made parallel to the weightbearing surface, thensliding the metatarsal head proximally, thus providing axialdecompression. The Weil osteotomy has recently gained inpopularity based upon the simple technique, stable fixation,excellent union rates, and predictable results.Indications for the Weil osteotomy have been extendedto include a relative long or plantarflexed metatarsal(s),transverse plane deformities of the metatarsophalangealjoint, subluxation/dislocation of the metatarsophalangeal(MTP) joint, crossover toe deformity, correction of arheumatologic deformity at the MTP joint and generalizedrecalcitrant metatarsalgia, which is refractory toconservative care (Figures 1-5).The overall physical examination must include theevaluation of concomitant deformities such as hammertoecontractures, hallux valgus, and hypermobility of the firstray. If these deformities are present, they must be surgicallyaddressed as well.The Weil osteotomy has replaced a number ofpreceeding osteotomies by its ability to shorten themetatarsal head without elevation or depression of themetatarsal head. The shortening and transverse planeposition can be carefully controlled intra-operatively. Amini-C arm may be employed to check the position of thecapital fragment in surgery. The osteotomy is usuallystabilized with a solitary screw driven from dorsal toplantar in the metatarsal head. The advantage to thisosteotomy is the decompression of the metatarsophalangealjoint and the resultant relaxation of thesurrounding soft tissues. Generally the osteotomy is mostoften used on the second metatarsal. However, the sameTable 1CAUSES OF METATARSALGIAPrimaryPlantar soft tissue lesionsAbnormal metatarsal parabolaMorton’s footNeuromaTraumaBrachymetatarsiaBone TumorsSecondaryIatrogenicFirst ray shorteningMetatarsal head resectionNeurogenicReferred painTarsal tunnel syndromeOsteoarthritisRheumatoid arthritisAtrophied plantar fat padStress fractureCapsulitis/bursitis/tedinitisFrieberg’s infractionFoot structure and functionPes cavusPes planusInappropriate shoegear

10CHAPTER 3considerations including length patterns, transverse planedeformities, subluxations, and intractable plantar skinlesions sometime merit the osteotomy to be preformed onthe third and fourth metatarsal.Possible complications of the Weil osteotomy includea dorsiflexed, nonpurchasing toe, pain on MTP jointdorsiflexion, reduced MTP joint range of motion,proximal interphalangeal joint contracture and a floppytoe. The relaxed tension of the plantar fascial insertion atthe base of the proximal phalangeal base may produce afloating toe. Long or prominent plantar fixation can alsocause postoperative pain and stiffness and needs to beremoved once the osteotomy is healed.Figure 1. Preoperative and postoperative view of along second metatarasal.Figure 2. Preoperative and postoperative view of ashortened first ray.Figure 3. Preoperative and postoperative view ofhallux varus.Figure 4. Preoperative and postoperative view ofhallux abducto valgus with second ray adductus.

CHAPTER 3 11Figure 5. Preoperative and postoperative view ofdigital adductus.TECHNIQUE TIPS AND PEARLSA 3.5- to 4.0-cm linear incision is made over the distalthird of the lesser metatarsal ending at the base of theproximal phalanx. This will reduce the chance of scar formationthat can contribute postoperative dorsal contracture.If digital work is done at the same time, a lazy-Sincision is made over the MTP joint as the incision endsdorsally over the middle phalanx.The extensor tendons are then retracted laterally andthe dorsal periosteum and capsule are incised with the toedorsiflexed to protect the articular cartilage. The collateralligaments are partially incised to fully expose the metatarsalhead. They do not need to be completely resected. Next,a McGlamry elevator may be used to release the plantarplate adhesions at the joint especially in the case of asignificant contracture. The McGlamry elevator strips theplantar synovial attachments (vincula), allowing theplantar plate to shift more proximally with the osteotomy.There is rarely vascular compromise to the capital fragmentand avascular necrosis of the head is extremely rare.The McGlamry elevator can double as a retractor forthe ensuing osteotomy. The head should be fully visualizedbefore the osteotomy is made. The osteotomy is started2-mm inferior to the most dorsal aspect of the articularcartilage at an approximately 25° angle with respect to themetatarsal shaft. The osteotomy can be as long as 2.5- to3-cm in standard foot conditions.The plane of the osteotomy is made parallel to theground as if the foot was bearing weight. The angle of theosteotomy may vary according to the angle of themetatarsal declination. The angle of the osteotomy mustincrease toward the more lateral metatasals because theyare less plantarflexed than the second metatarsal.In severely plantarflexed metarsals, a second osteotomyis performed in effect to remove a slice of bone to furtherdorsiflex the capital fragment. An easier, more stable tip isto use a double saw blade or a thicker saw blade to obtain thesame goal of removing more bone to dorsally elevate themetatarsal head.When the osteotomy is completed, the metatarsal headwill suddenly shift to a more proximal position. There is acertain neutral position that reflects the relaxation of thesurrounding soft tissues that feels just right. Then withmanual pressure, a solitary K-wire or bone clamp is used totemporarily fixate the osteotomy. The position can bechecked by fluoroscopy at this time. The metatarsal headposition can be changed from 2- to 10-mm with 3- to5-mm being the normal amount of shortening.The osteotomy can be slightly angulated in the frontalplane if more dorsal excursion is desired. The head can alsobe rotated and translocated somewhat in more difficulttransverse or crossover toe cases. However, too muchmanipulation of the osteotomy or displacement of capitalfragment can sacrifice the overall stability of the construct.Do not be too extreme. A standard parallel Weil osteotomy,without any geometric modifications has been found to besuccessful in treating most forefoot malalignments.A solitary screw driven from proximal dorsal to distalplantar into the metatarsal head is usually sufficient. Thereare a multitude of different screws that can be used for thispurpose including the twist-off screw by Depuy. I prefer theSynthes modular hand set screws. These are noncannulatedwith a smaller head that is not prominent. They haveexcellent purchase due to the increased thread excursion,and they can be minimally tapped as they will self tap oncestarted into the capital fragment.The one consensus regarding screws is that a 12-mmscrew will fit in the vast majority of adult metatarsalswithout penetrating the plantar metatarsal head. Thisobviates the need to measure the pilot hole. I usually usea 2.0-mm screw in most adults for fixation of the Weilosteotomy. A 2.4-mm screw is useful in larger adults anda 1.6-mm can be used in a very slight individual. Theresulting dorsal overhanging bone ledge is then resectedwith a rongeur.Postoperatively, most patients are maintained partialweightbearing in an Orthowedge shoe using crutches or awalker to support their upper body weight. The patient canbe transferred into a standard surgical shoe at 4 weeks withearly radiographic signs of osseous healing. A severely

12CHAPTER 3dorsiflexed toe that is released may benefit from a 0.045K-wire across the MTP joint for 4 to 6 weeks. In mildercases, splinting or a Betadine splint is useful for the initialthree weeks. The patient should initiate rigorous sagittalplane exercises once early bone healing has occurred.The most common reported complication is thefloating toe. One theory suggests the Weil osteotomychanges the center of rotation of the MTP joint. Theinterosseous muscles then act more as dorsiflexors thanplantarflexors contributing to a nonpurchasing toe. Iusually will perform a proximal interphalangeal jointarthrodesis in concert with a Weil osteotomy whenindicated. I strive to avoid excessively shortening the toewhile performing the arthrodesis to preserve the strongerplantarflexory lever arm associated with an arthrodesis.The arthrodesis should be mildly flexed by bending theK-wire after it is inserted into the toe. In addition, the longextensor tendon is lengthened in a Z-plasty fashion as areall of the soft tissues that are dorsally contracted with thesequential release. A K-wire can be carefully passed acrossthe reconstructed metatarsophalangeal joint to either sideof the screw when necessary. These measures greatlydecrease the incidence of a nonpurchasing toe.Significantly unstable, dorsiflexed toes will require aconcomitant flexor tendon transfer.The Weil osteotomy is an effective and safe procedurefor the treatment of plantar, central metatarsal symptomscaused by a relatively long metatarsal. Complications can becontrolled with a judicious amount of shortening ofthe metatarsal while avoiding plantar depression of thecapital fragment. Ancillary procedures directed at correctingcoexistent pathology must be considered in compounddeformities.