Fig. 13.1
(a) A lateral radiograph projection demonstrating a patient who suffers from TMT-1 hypermobility/instability. Note the dorsal cortex of the first metatarsal in comparison to the second metatarsal leading to an elevated first metatarsal. (b) An appearance of a “long first metatarsal” on a AP radiograph secondary to the hyper mobility. (c) Patient who presents with a HAV deformity bilaterally as well as a sub two callus lesion on both feet. (d) Note the lack of weight bearing under the first metatarsal causing the increased pressure to the sub-second metatarsal. The increase in sub-second metatarsal is secondary to the increase in the intermetatarsal (IM) angle, the elevatus of the first metatarsal (the first ray is not bearing the needed weight) along with a tight posterior muscle group increasing the forefoot load to the second metatarsal
Fig. 13.2
This is an AP radiograph from a patient who presents with a recurrent hallux abducto valgus deformity who had a previous distal metaphysical osteotomy performed. Note the diastasis of the base of the metatarsals and cuneiforms, a valgus rotation of the hallux and sesamoid complex, a previous stress fracture experienced by this patient from second metatarsal overload because of the increase in intermetatarsal angle (increasing the load to the second metatarsal as the first is not bearing the weight), and hypermobility/instability of the first ray
In reality there is no consensus or consistency in the clinical measurement or definition of first ray hypermobility, and that is why we question the utility of this measure as a primary indication for tarsometatarsal level of correction for HAV. As discussed in Chaps. 2 and 6, the main site of mobility of the first ray is at the naviculocuneiform and talonavicular joints with a minority of motion at the TMTJ . The first metatarsocuneiform arthrodesis in reality is indicated to treat moderate to severe hallux abducto valgus as well as high levels of deformity with or without the presence of hypermobility. The main utility of the procedure is that it has the advantage of providing correction at the apex of the deformity [17, 18]. In addition, TMTJ is a convenient location to address all planes of the deformity concurrently including the transverse, the sagittal, and the frontal plane resulting in complete anatomic correction. Patients with small IMA may have significant frontal plane deformity which is why, like with hypermobility, the degree of IMA is not used as a prime indication. Sesamoid axial radiographs are recommended to assess the overall position of the first metatarsal in the frontal plane. Dayton et al. found in a case study of 25 patients that all patients had a component of frontal plane deformity. Correcting the frontal plane resulted in change in the IMA of 10.1°, hallux abduction angle (HAA) of 17.8°, and proximal articular set angle (PASA ) of 18.7° [19]. Dayton et al. reviewed the data on 35 consecutive patients who underwent triplane bunion correction including derotation of the metatarsal. They found the mean amount of varus (supination) rotation performed during correction was 22.1 ± 5.2°. The mean amount of intermetatarsal angle reduction achieved was 6.9 ± 3.0°. The tibial sesamoid position changed by a mean of 3.3 ± 1.2° [20]. DiDomenico et al. evaluated the correction of the IMA and sesamoid position with frontal plane derotation and found by derotating the metatarsal that there is a significant improvement in both IMA and sesamoid position [21]. Other indications for first metatarsal–cuneiform arthrodesis include pes planus correction, treatment of degenerative joint disease (DJD) , and revision HAV procedures [10, 16, 22, 23] (Fig. 13.3a–c).
Fig. 13.3
(a) This is an AP radiograph of a patient who underwent a closing base wedge osteotomy of the first metatarsal with K-wire and screw fixation. The patient experienced a fracture and displacement of the osteotomy site with malalignment. (b) This is an AP radiograph of correction of photo 12 A who underwent a revision Lapidus procedure to correct the malalignment and displacement of the closing base wedge osteotomy. (c) A clinical photo demonstrating good anatomical alignment of the recurrent HAV deformity. Note the previous scars from the previous surgeries. There is only an incision at the tarsal-metatarsal joint which obtained good anatomical alignment and reduction of the deformity in all three planes. No dissection (lateral release) or medial eminence resection was performed
Contraindications include a short first ray, because some degree of shortening is inevitable with resection of the joint, therefore further shortening an already short ray. Additionally, the procedure should be avoided in individuals with open growth plates.
The authors want to point out that a short first ray is very unusual in feet that have not been affected with trauma or previous surgery. Oftentimes what may appear to be a short first ray on a “single snap shot projection ” more likely than not is not truly a short ray. Considerations that must be addressed when evaluating radiographs are what was the patient’s position of their foot and was it fully loaded at the time of the X-ray? What was the angle of the beam relative to the foot at the time of the X-ray? Does the patient have more of a flatfoot or a high-arched foot? If a patient has more of a flatfoot, the radiograph projection will more likely than not appear long, and if patient presents with more of a high-arched foot, the first metatarsal will be more plantarflexed and appear relatively short. The surgeon needs to take this into consideration and rely on clinical evaluation as much as the radiographic evaluation.
Technique #1
Preferred Technique: Lawrence A. DiDomenico and Daniell N. Butto
An incision is made over the metatarsal–cuneiform joint approximately 4–6 cm in length. There is no incision at the level of the first metatarsophalangeal joint or in the IM joint space. The tarsal–metatarsal incision is deepened in the same plane using sharp and blunt dissection. All bleeders are identified and ligated as necessary. The incision is carried down exposing the metatarsal–cuneiform joint. The tarsal–metatarsal ligaments are resected using a rongeur exposing the joint. Two mini Hohman retractors are used for the soft tissue retraction. Next the articular cartilage of the metatarsal and cuneiform sides of the joint are resected. The initial joint resection is performed on the first metatarsal articular surface. The first metatarsal articular surface is denuded first as this is the most distal and the most unstable segment. This resection is made perpendicular to the long axis of the first metatarsal and parallel to the existing metatarsal base. There is no correction made within the first metatarsal segment, as there is no deformity in the first metatarsal in typical HAV deformity. Thus, the articular joint resection needs to be kept consistent and parallel with the natural-occurring anatomy. The base of the first metatarsal is concave; therefore, the amount of cartilaginous resection on the base of the first metatarsal will need to be slightly greater than the amount on the convexity of the natural-occurring articular surface of the cuneiform. The corrective articular resection is made at the distal aspect of the convex-shaped cuneiform. The correction is made with a slight change in angular resection in the transverse plane. The frontal and sagittal planes are later corrected via reduction and appropriate positioning of the tarsal–metatarsal joint (Fig. 13.4).
Fig. 13.4
These are the articular surfaces of the base of the first metatarsal and cuneiform following joint resection in preparation of performing a Lapidus procedure
Prior to reducing the joint into the appropriate desired position, a significant amount of time should be spent with joint preparation to ensure good bony healing. The metatarsal base and distal cuneiform as well as the medial aspect of the second metatarsal base are prepared. The authors use a laminar spreader for distraction between the first metatarsal and cuneiform. A pituitary rongeur is used to debride the cortex of the medial wall of the second metatarsal. It is imperative that the surgeon is diligent to ensure that the subchondral plate is penetrated demonstrating good bleeding at both the metatarsal and cuneiform. The joint preparation is extremely important in efforts to obtain a bony union and to avoid a delayed and nonunion (Fig. 13.5).
Fig. 13.5
An intraoperative view demonstrating bone debridement of the medial base of the second metatarsal in preparation for fixation of a Lapidus procedure
Next, the frontal plane is addressed. The surgeon derotates the hallux out of valgus (in a varus direction to a neutral anatomic position) in order to get the nail plate to be parallel with the ground. This derotation allows for the entire hallux, sesamoid, and first metatarsal complex to be rotated from a position of valgus and into a neutral position as one unit. This results in the sesamoid complex repositioned under the first metatarsal; the hallux is taken out of a valgus position into a anatomic neutral position. This rotation will be clinically evident at the tarsal–metatarsal joint as well as under fluoroscopy. Because there is no dissection at the first metatarsophalangeal joint (medial eminence resection or sesamoidal dissection), the maintenance of the soft tissues allows for the integrity of the hallux, sesamoids, and metatarsal to function as one unit. By maintaining the integrity of the soft tissues, the first metatarsal phalangeal joint maintains stability and allows the surgeon to manipulate and reposition the metatarsal phalangeal joint and the first metatarsal into a corrective anatomical alignment. If the soft tissues are dissected (historically know as a “lateral release” and medial eminence resection), this destabilization of the soft tissues will not allow the surgeon the ability to rotate and position the first metatarsal phalangeal joint and first metatarsal into anatomic alignment. The sesamoid correction can be observed under fluoroscopy at this time. The sagittal plane reduction technique is performed by stabilizing the hind foot, while the surgeon dorsiflexes the first metatarsophalangeal joint initiating the windless mechanism. This hind foot stability allows the surgeon to apply retrograde forces to the plantar tarsal–metatarsal joint and allows for the first metatarsal to plantarflex to a natural-occurring level, parallel with the lesser metatarsals. Once the surgeon has the hallux, sesamoid, and metatarsal rotated to a neutral desirable position (frontal plane reduction), and the first metatarsal sagittal plane corrected, the surgeon can use his or her thumb against the first metatarsal to manually reduce the first intermetatarsal angle in the transverse plane. The primary surgeon must ensure that the first metatarsal is in the desired position, which is essentially rotated out of valgus, and parallel with the second metatarsal in both the transverse and sagittal planes. Next a 2 mm smooth K-wire is used to stabilize the reduction and position. The first K-wire is positioned from the central proximal one-third of the first metatarsal into the cuneiform. Because of appropriate positioning of the tarsal–metatarsal joint, it is not unusual to see dorsal gapping at the tarsal–metatarsal joint. Subsequently, while maintaining position in all three planes, a second K-wire is inserted into the medial first metatarsal head and into the lesser metatarsals ; this serves to prevent derotation in the frontal plane, maintains reduction in the transverse plane, as well as maintains confirmed desired position of the first metatarsal parallel to the second metatarsal (prevents elevation of the first metatarsal relative to the lesser metatarsals in the sagittal plane). If the surgeon feels a need to obtain more correction in the frontal plane, the temporary fixation K-wires can be backed out, and an additional K-wire can be inserted into the first metatarsal medial and lateral cortex with the K-wire in the direction of inferior medial to superior lateral. Once the K-wire penetrates the far cortex of the first metatarsal, the K-wire can be used as a rotation device and rotate the metatarsal into more of a neutral position (out of valgus and in a varus direction) and insert the K-wire into the lesser metatarsal to stabilize the position. In many cases, a large Weber clamp may be used to assist, increase, or maintain the reduction. When using the large Weber clamp, the surgeon must be sure not to change the sagittal plane relationship between the first and lesser metatarsals. The position is checked both clinically as well as under fluoroscopy to confirm acceptable alignment (Fig. 13.6a, b).
Fig. 13.6
(a) An intraoperative lateral radiograph demonstrating temporary K-wire fixation and a large Weber clamp for stabilization and reduction while the surgeon is drilling for the “home run” screw. Note the origin of the drill hole in the first metatarsal is as distal as possible, and it exits at the medial inferior cuneiform inferior to the navicular. The sagittal plane correction is well visualized as there is good bone-to-bone contact at the inferior metatarsal and cuneiform along with dorsal gapping at the metatarsal cuneiform superiorly indicating good sagittal plane correction of the first ray. The dorsal gapping will be backfilled with autogenous calcaneal bone graft. (b) An intraoperative AP radiograph demonstrating temporary K-wire fixation and a large Weber clamp for stabilization and reduction of the intermetatarsal angle in the transverse plane
The recommended fixation options for this technique are three solid long cortical interfragmentary compression screws or a solid cortical interfragmentary compression screw along with a medial plate. Regardless of the construct, the first screw is the most important screw; this is often referred to as the “home run screw” [24]. This screw should be a solid long cortical screw with preference size of a 3.5 or 4 mm. A trough is created into the mid-dorsal side of the first metatarsal approximately in the proximal one-third to one-half of the metatarsal [25]. A high-speed bur is used to create a notch in the cortical bone as described by Manoli and Hansen [25]. The notch allows for drilling difficult angles such as the first metatarsal to the first cuneiform. The first metatarsal has a declination making drilling without the notch difficult, and this technique allows the surgeon to control the screw angle and also allows the undersurface of the screw head to fit better at the level of the cortex or slightly below as well as avoid external pressures such as shoes from the thin skin of the dorm of the foot, help prevent stress risers, and avoid fracturing the cortex.
The first drill is either 4.0 mm for a 4.0-mm cortical screw or 3.5 mm for a 3.5-mm cortical screw and is drilled into the first metatarsal and stopped at the cuneiform. The next drill is either 2.9 mm for the 4.0-mm cortical screw or 2.5 mm for the 3.5-mm cortical screw and drilled into the cuneiform. The drill is aimed for the inferior, medial aspect of the cuneiform (based on the shape of the cuneiform, the largest cross section of the bone is in the medial cuneiform). This screw should have a bicortical purchase; this screw provides interfragmentary compression at the plantar aspect of the joint or the tension side of the foot, and the long screw provides leverage and resistance to ground reactive forces. This allows for excellent reduction at the base of the tarsal–metatarsal joint most often leaving some dorsal gapping of the tarsal–metatarsal joint. When a three-screw construct is desired, the next screw is inserted from the medial proximal one-third of the first metatarsal into the base of the second metatarsal with the respective drill sizes for a 3.5-mm or a 4.0-mm cortical screw. The initial drill is the oversized drill through the first metatarsal, and the second drill is the undersized drill into the second metatarsal and/or possibly the lesser metatarsals in order to obtain a screw purchase and allow the surgeon to dial in with the desired intermetatarsal angle reduction. Oftentimes a washer will be applied with this screw, which provides greater reduction of the IM angle. The third screw is placed from the most proximal dorsal position of the cuneiform aiming into the medial proximal first metatarsal. This screw also should be as long as possible for obtaining leverage and resistance to ground reactive forces. The longer the interfragmentary screw, the greater the dispersion of forces and more counteraction of the tensile forces. The key to the placement of this screw is to start distally on the metatarsal and aim for the plantar-medial cortex of the medial cuneiform. The construct should be checked under fluoroscopy to confirm adequate reduction. The surgeon should check for intercuneiform instability, and if intercuneiform instability is identified, then intercuneiform joint preparation should be performed, and the medial to lateral screws should be inserted into the intermediate and/or lateral cuneiform for additional stability. It has been the authors’ experience that grossly hypermobile feet and flatfoot deformities often present with intercuneiform instability [26] (Figs. 13.7a, b and 13.8).
Fig. 13.7
(a) This is a postoperative lateral radiographic projection of a patient who had a Lapidus procedure with a three-screw technique and a percutaneous calcaneal displacement osteotomy performed. With respect to the Lapidus fixation, note the “home run” screw is long, it provides interfragmentary compression, and it is parallel to the ground (providing a “beam effect”). The cuneiform to the first metatarsal also is long and provides bicortical interfragmentary compression too, and the medial to lateral screw inserts into the base of the second metatarsal also with bicortical interfragmentary compression. Note the screw heads are countersunk below the cortex because of the thin soft tissue envelop of the skin in the foot and to provide relief from external pressures such as shoes 42. (b) This is a postoperative AP radiograph of a patient who had a Lapidus procedure performed with a three-screw technique. Notice the length of the “home run” screw – the authors recommend between 50 and 60 mm of length. The “home run” screws are inserted in the most medial aspect of the inferior cuneiform (area of most bone in the cuneiform). Because of the thin soft tissue envelope of the foot, the transverse screw head is also countersunk to avoid external pressures such as shoe gear. The transverse screw also demonstrates a bicortical purchase. A washer is used with this screw to aid in the reduction of “dialing in” or assisting with the intermetatarsal angle reduction
Fig. 13.8
A hallux varus deformity: this is a patient who had a Lapidus procedure performed with distal soft tissue balancing which lead to a hallux varus deformity. In this chapter, the authors do not recommend distal soft tissue balancing or resection of the medial eminence of the first metatarsal. It has been the authors’ experience that this is not needed to obtain an adequate reduction of the hallux valgus deformity and one cannot obtain a hallux varus if the distal soft tissue procedure is not performed
When a medial-based plate or locking plate is used in conjunction with an interfragmentary compression screw, the plate is applied to the medial first metatarsal–cuneiform joint. Following the insertion of the “home run screw,” the initial screws are placed proximal in the medial cuneiform of the plate in combination with locking and nonlocking screws. The distal screws are placed into the metatarsal with a combination of locking and nonlocking screws. Similar to the three-screw technique, an interfragmentary compression screw can be applied within the plate from medial to lateral into the second and/or lesser metatarsals. This interfragmentary compression allows the surgeon to reduce the IM angle, and the plate essentially becomes an excellent reduction tool acting similar to a large washer. The plate is placed to span the metatarsal and cuneiform. Screws are placed through the plate and span the cuneiforms proximally, and an intermetatarsal screw is placed at the base of the first and second metatarsals. The medial plate acts as a “large washer” aiding in the reduction of the intermetatarsal angle in the transverse plane. With the proximal portion of the plate anchored well into the cuneiform, the distal portion of the plates mimics a “large washer” as the interfragmentary screws placed at the proximal portion of the first metatarsal allow the surgeon to “dial in” with the reduction of the intermetatarsal angle, and the remaining distal screws lock the reduction in place. Additionally, it provides stability from frontal plane rotation and intercuneiform instability. Often the authors get questioned if the intermetatarsal screw is problematic, painful, or if it breaks/fractures. The authors (unpublished at this time) reviewed 105 cases and found eight cases in which there was a fracture in the screw. Those patients who experienced a fractured screw were clinically/symptomatic insignificant. The construct should be checked under fluoroscopy to confirm adequate reduction (Fig. 13.9a–i).
