Patient selection for a closing base wedge or opening base wedge osteotomy is of utmost importance. All procedures have advantages and disadvantages which must be taken into consideration for the individual patient. The CBWO has been described for juvenile hallux valgus . Some patients with juvenile hallux valgus have an increased proximal articular set angle (PASA), and the CBWO may further increase the PASA in these patients [23]. Elderly patients that have difficulty remaining non-weight bearing are often best suited with a procedure that allows early weight bearing. We take preoperative vitamin D in postmenopausal women, and vitamin D deficiency or insufficiency is treated prior to hallux valgus correction with basilar osteotomies.

Basilar osteotomies are performed on patients with high IM angles, and these patients often have hypermobility, but this finding may not be a contraindication for basilar osteotomies if the hypermobility is not severe. Rush et al. (2000) noted a reduction in hypermobility after correction of the intermetatarsal angle in seven cadaveric specimens with the windlass mechanism engaged [24]. Realigning the first metatarsal head over the sesamoids may allow the plantar aponeurosis to prevent collapse of the medial column. Coughlin et al. (2004) measured first ray sagittal motion with a Klaue device in 12 cadaveric specimens before and after bunion correction with a crescentic osteotomy and a distal soft tissue release. In their study the mean IM angle was reduced from 12.9° to 6.8° resulting in a reduction in the first ray sagittal plane motion from 11.0 to 5.2 mm [25]. To reiterate their results, Coughlin et al. (2007) measured first ray motion preoperatively and postoperatively in 122 feet undergoing a proximal crescentic osteotomy and a distal soft tissue release with mean 27 month follow-up. The mean IM angle changed from 14.5° to 5.4° with first ray mobility diminishing from 7.2 to 4.5 mm [26]. Faber et al. (2013) found no difference in recurrence between a Hohmann osteotomy and a lapidus bunionectomy at long-term follow-up, and these findings extended to a subgroup of 63 patients with preoperative hypermobility [27]. In contrast, Haas et al. (2007) found more loss of correction with the closing base wedge osteotomy compared with the lapidus arthrodesis at 11 month follow-up, 2.55° versus 1.08°, respectively [28]. Oravakangas et al. (2016) had good maintenance of correction at 5.8 year follow-up with the OBWO , and they did not feel hypermobility adversely affected their outcomes [29].

Patients with pronation of the metatarsal head are another subset of patients that may benefit from a lapidus bunionectomy over a basilar osteotomy. Okuda et al. (2009) noted that pronation of the first metatarsal head identified as a “round sign” is associated with recurrence [30]. This coronal plane rotation is more common in patients with hallux valgus compared with controls. Sesamoid axial views show the degree of pronation preoperatively, and there is a small subset of patients with severe hallux valgus without metatarsal pronation. Kim et al. (2015) found that 87.3% of hallux valgus patients had first metatarsal pronation greater than 15.8°. The remaining patients in their study had first metatarsal pronation less than 15.8°, and these patients may not require triplane correction. The control group in their study had a mean 13.8° of first metatarsal pronation [31]. It has been hypothesized that as pronation occurs, the medial aspect of the first metatarsal head is no longer supported by the sesamoid apparatus [32]. Sesamoid relocation may promote reduction of metatarsal head pronation by supporting the medial first metatarsal head, but this requires further study. It is not known if pronation reduces with osteotomy correction. This theory has not been studied, and we choose to perform a lapidus with triplane correction to address first metatarsal pronation.

A significant elevation in PASA may be another relative contraindication for both the CBWO and the OBWO . Both basilar osteotomies increase PASA by providing angular correction of the first metatarsal distal to the CORA . Mid-shaft and distal osteotomies that correct the IM angle through translation maintain PASA with correction. Paczesny et al. (2009) found poor midterm correction of the IM angle following the CBWO in patients with an elevated PASA. The same study found that the Scarf osteotomy provided adequate midterm correction of the IM angle in patients with elevated PASA [33]. Shurans et al. (2009) noted an association between high preoperative PASA and recurrence with the OBWO [34]. Iyer et al. (2015) had a higher rate of recurrence compared with previous OBWO reports. Eleven of seventeen (64.7%) patients had recurrence defined as greater than 5-degree increase in the hallux valgus angle on weight-bearing x-rays in the postoperative period. Elevated PASA had a statistically significant association with recurrence in their study [35].

Preoperative x-rays are taken to rule out joint space narrowing of the first metatarsophalangeal joint or a fault at the first metatarsocuneiform joint identified as plantar gapping. Patients with joint space narrowing have a more predictable outcome with first MTPJ arthrodesis. Patients with a fault at the first metatarsocuneiform joint can develop a forefoot-driven pes valgus, and a lapidus can provide correction. Coughlin et al. found a reduction in hypermobility following hallux valgus correction with a first metatarsal osteotomy, but there was little correction in plantar gapping at the first metatarsocuneiform joint on postoperative radiographs.

Another useful x-ray view is the sesamoid axial view. The closing base wedge osteotomy can be utilized with high 1–2 intermetatarsal (IM) angles in the absence of metatarsal pronation on the sesamoid axial view. The sesamoid axial view identifies significant sesamoid subluxation requiring more aggressive soft tissue balancing. Sesamoid axial views also rule out degenerative joint disease of the sesamoid apparatus. A first MTPJ arthrodesis is performed if there is degenerative joint disease of the sesamoid articulation with the first metatarsal head.

On clinical exam the first metatarsocuneiform joint is brought through range of motion. Severe hypermobility or pain with range of motion may require a lapidus. If there is preoperative hyperkeratosis, metatarsalgia, lesser metatarsal stress fractures, or thickening of the second metatarsal, an opening base wedge osteotomy or a lapidus may restore weight-bearing forces through the medial column most effectively. We have used the OBWO to reduce weight-bearing forces through the second ray in the presence of plantar plate pathology or metatarsalgia (Fig. 10.2). The lapidus may be the better option if there is plantar gapping of the first metatarsocuneiform joint. A rigid first metatarsocuneiform joint that does not reduce in the transverse plane will not provide added correction when the retrograde force from the hallux is reduced with hallux valgus correction. These patients require more aggressive IM angle correction and may benefit from proximal correction such as a basilar osteotomy.

An incision is made directly medial to the extensor hallucis longus (E HL) from the first metatarsocuneiform joint to the base of the proximal phalanx. The medial dorsal cutaneous nerve finishes crossing the extensor hallucis longus (EHL) tendon on average 16 mm proximal to the first metatarsocuneiform joint (range, 0–41 mm) and can be encountered in the proximal aspect of the incision if the incision is too medial [36]. The dorsal venous arch is retracted proximally. Following retraction of the dorsal venous arch, a full-thickness incision down to the bone can be made just medial the EHL tendon. Periosteal reflection is limited to prevent avascular necrosis of the first metatarsal. The nutrient artery enters the lateral aspect of first metatarsal at the junction of the proximal and middle third of the bone near the site of the CBWO . Care is taken not to over penetrate the lateral cortex with the saw blade. Chuckpaiwong and Korwutthikulransri (2013) described the course of the first intermetatarsal artery which can be injured with basilar osteotomies [37]. They described a triangular safe zone with the first metatarsocuneiform joint, plantar cortex of the second metatarsal, and intermetatarsal artery providing borders for the safe zone. Additional soft tissue procedures such as medial capsulorrhaphies and lateral releases have a cumulative effect on the reduction in blood flow to the first metatarsal [38]. Of note, avascular necrosis is rarely reported as a complication of basilar osteotomies and is more frequently reported as a complication of distal metatarsal osteotomies.

In our practice, a lateral release is performed if there is adequate reduction of the IM angle with residual sesamoid displacement. Lateral release in conjunction with the CBWO is associated with improved correction but also increased first metatarsophalangeal joint stiffness [39]. Kim et al. [31] found that sesamoid subluxation was associated with higher IM angles [31]. Achieving sesamoid relocation has been associated with lower recurrence rates in a study by Okuda et al. (2015). By definition sesamoid subluxation requires attenuation of the medial metatarsosesamoid ligament [30]. When significant sesamoid subluxation is present, we perform adjunctive lateral release of the lateral metatarsosesamoid ligament and adductor tendon with imbrication of the medial metatarsosesamoid ligament and medial collateral ligament to maintain sesamoid relocation and prevent recurrence. For soft tissue balancing, release of the adductor tendon is performed from the proximal aspect of the fibular sesamoid. Owens and Thordarson (2001) noted the adductor tendon could not be differentiated from the flexor hallucis brevis when adductor release was performed from the distal aspect of the sesamoid [40]. The medial capsulorrhaphy is performed distal to the medial metatarsosesamoid ligament. We are conservative with the amount of imbrication from the medial capsular apparatus because this can reduce the range of motion and alter joint mechanics. We do not rely on the medial capsulorrhaphy to achieve our correction.

The closing base wedge osteotomy is performed perpendicular to the weight-bearing surface of the foot to ensure no dorsal or plantar translation with correction through the osteotomy. An axis guide can be utilized to ensure the saw cuts are perpendicular to the weight-bearing surface. With the CBWO , the medial hinge acts as the center of rotation. Laporta et al. (2015) described the apex of deformity or center of rotation of angulation (CORA ) of hallux valgus occurring in the proximal tarsus [41]. The more proximal the medial hinge, the closer the correction is to the CORA resulting in less medial translational deformity and less of an increase in PASA. The medial hinge of the CBWO is marked 8–10 mm distal to the first metatarsocuneiform joint to allow plate fixation. If the medial hinge is too far distal, then the corrective power of the osteotomy is reduced.

The closing base wedge osteotomy can be performed oblique or transverse to the first metatarsal. There is a trade-off because a more oblique cut leaves more room for fixation with greater bone contact area, while a more transverse cut requires less bone resection laterally for a given angle of correction with less shortening. We prefer a slight obliquity to the cut with plate fixation to allow variable angle locking screws to be directed away from the first metatarsocuneiform joint. Following the saw cuts, the osteotomy can be closed with reduction forceps. This allows the surgeon to assess the correction and further feather the lateral cortex if increased correction is desired.

The proximal oblique sliding closing wedge osteotomy (POSCOW) is a modification of the CBWO that was developed to maintain the length of the first metatarsal. Distal medial translation of the osteotomy offsets translational deformity imparted by correcting the osteotomy distal to the CORA . The authors that proposed the procedure noted a learning curve with more complications occurring in the initial patients within their series [42].

Similar to the CBWO , the OBWO is performed perpendicular to the weight-bearing surface to prevent malreduction in the sagittal plane. The lateral hinge acts as the center of rotation, and a more proximal lateral hinge is closer to the CORA of the deformity. We keep the lateral hinge 8–10 mm from the first metatarsocuneiform joint. Han et al. (2015) noted more medial translation of the first metatarsal head with a transverse OBWO compared with an oblique OBWO [43]. In their study, the lateral hinge for the transverse OBWO appeared to be more distal on the first metatarsal imparting greater medial translation. Assuming the same lateral hinge is utilized, a more oblique OBWO requires more bone for a given angle of correction and can provide greater lengthening of the first metatarsal.

Two screws can be used for fixation in a CBWO with a compression screw perpendicular to the osteotomy and an anchor screw perpendicular to the first metatarsal. There are different recommendations regarding which screw should be inserted first. The authors prefer to insert the compression lag screw first because the compression is perpendicular and less likely to displace the osteotomy with initial screw insertion. The proximal anchor screw is inserted second. 2.7 mm cortical screws allow revision with larger screws if there is poor screw purchase. Fillinger et al. (1998) loaded saw bone models to failure to compare fixation strength for the closing base wedge osteotomy and the crescentic osteotomy. The use of saw bone models was a weakness of the study. Load to failure of the CBWO was 39.6 N with one 2.7 mm screw and 43.1 N with two 2.7 mm screws. The crescentic osteotomy had a load to failure of 67.7 N with one 4.3 mm screw. Neither osteotomy achieved 25% of the load to failure of the control model indicating the inherent weakness of the osteotomies with screw fixation [44]. Biomechanical testing by Landsman and Vogler (1992) agreed that screw fixation provides inadequate initial stability for the CBWO [45]. Smith et al. (2014) reviewed load to failure in 40 biomechanical testing bones. Twenty bones had an oblique CBWO fixated with two 2.7 mm cortical screws, and 20 bones had an oblique CBWO fixated with a four-hole locking plate. Mean load to failure for the plate construct was significantly greater than the mean load to failure for the screw construct, 190.0 ± 70 N versus 110.3 ± 20.3 N, respectively [46]. Plantar plate fixation with a two-hole one-third tubular plate has also been tested in the fixation of a biplanar closing base wedge osteotomy. Load to failure was tested in ten matched cadaver feet and compared with 4.0 mm cancellous screw fixation for the crescentic osteotomy. Load to failure was significantly higher with plantar plate fixation of the closing base wedge osteotomy, 127.2 ± 81.9 N versus 44.9 ± 43.3 N [47].

A locking plate provides greater stability compared with two screw fixation constructs for the closing base osteotomy. The authors prefer plate fixation because the locking plate neutralizes bending and shearing forces which may reduce the incidence of a dorsal malunion (Fig. 10.3). Locking plates allow a more transverse osteotomy to be performed which requires less bone resection for correction. If shortening is less of a concern, a more oblique osteotomy may allow lag screw fixation in addition to the locking plate. L-type or T-type plates provide at least two points of fixation proximally and at least 2 points of fixation distally (Fig. 10.3). Randhawa and Pepper (2009) described the degree of correction with different wedge sizes associated with L-type plate fixation. A 3.5 mm wedge plate provided a mean correction of 8.0°. A 4.0 mm wedge plate provided a mean correction of 9.0°. A 5.0 mm wedge plate provided a mean correction of 14.9° [48]. Data from this study allows the surgeon to measure angles preoperatively and decide on initial plate application intraoperatively. It is important to remember that the amount of the correction depends on the location of the lateral hinge and the obliquity of the osteotomy in addition to the graft size.

Screw fixation for the CBWO requires extended non-weight bearing. The patient is made non-weight bearing in a posterior splint for 10 days followed by non-weight bearing in a short leg cast until they are 6 weeks from the date of the procedure. Weight bearing in a CAM boot is continued for an additional 3 weeks. Patients can return to work at 8 weeks for sedentary jobs and at 11–12 weeks for jobs that require manual labor. With plate fixation for closing or opening wedge osteotomies, the patient is made non-weight bearing in a posterior splint for 10 days followed by heel weight bearing in a CAM boot for an additional 4 weeks. Patients can return to work at 6 weeks for sedentary jobs and at 10 weeks for jobs requiring manual labor. The patient begins active and passive range of motion of the first MTPJ when they are no longer immobilized in a short leg cast.

A meta-analysis of proximal first metatarsal osteotomy procedures identified 62 studies eligible for inclusion. Among proximal osteotomy procedures, the three most common major complications requiring revision are hallux varus (4.3%), recurrence (3.5%), and dorsiflexion malunion (2.5%). Major complications defined as complications that could require revision had an incidence of 12.8% in the study. Major complications were reduced with the use of locking plate fixation (5.5%). Major complication rates were 15.67% ± 3.22 for the closing wedge osteotomy and 14.29%± 4.10 for the opening wedge osteotomy. Complication rates were lower for the proximal crescentic osteotomy (11.69% ± 2.86) and the proximal chevron osteotomy (6.05% ± 1.62) [49].

Dorsal malunion is a significant complication associated with the closing base wedge osteotomy. Proximal metatarsal osteotomies provide a larger lever arm for high weight-bearing forces to act on the osteotomy. Lesser metatarsalgia and hallux limits are common sequelae associated with this complication. There is a wide variety in the incidence of dorsal malunion associated with the CBWO , and the variation may be related to fixation strength and weight-bearing status.

Lagaay et al. (2008) assessed reoperation rates for recurrent hallux valgus and hallux varus in a large health care system across multiple surgeons. The closing base wedge osteotomy (34 patients) had a higher reoperation rate than the lapidus bunionectomy (342 patients) or the Austin bunionectomy (270 patients), 8.82% versus 8.19% versus 5.56%, respectively. The difference in reoperation rate was more pronounced when solely taking into account cases of over- or under correction, 5.88% versus 3.21% versus 3.33%, respectively [50]. A limitation of the study was the small sample size of patients undergoing the CBWO . The closing base wedge osteotomy may be more prone to under- or overcorrection because it is difficult to remove the precise amount of bone to achieve the desired correction, and most surgeons do not translate the osteotomy to compensate for imprecise wedge resection.