Justin Fleming, DPM

A 22 year-old female presents to the office complaining of right foot bunion pain. The patient complains of pain progressing over the last year, with no relief from conservative treatments.

PMH: Anxiety

PSH: ORIF nasal fracture, extraction of wisdom teeth

FMH: Non-contributory

MEDS: Lexapro, Oral contraceptives

LOWER EXTREMITY PHYSICAL EXAMINATION

LEFT LOWER EXTREMITY: Patient presents with a clinically significant bunion deformity. There is positive bump pain with associated erythema. There is no pain or crepitus with ROM of the 1st MPJ. There is positive tracking of the hallux during ROM. Hypermobility is noted at the 1st metatarsal-cuneiform joint. No hammertoe deformity is present. There are palpable pedal pulses that are graded +2/4 at the dorsalis pedis and posterior tibial arteries. Capillary refill time is less than 3 seconds. Protective sensation is intact to lower extremity digits.

IMAGING STUDIES:

Weight bearing images obtained of the left foot demonstrate evidence of a moderate to severe hallux abductovalgus deformity. There is an increase in the inter-metatarsal angle as well as an abnormal sesamoid position. The 1st metatarsal-phalangeal joint space remains preserved with no signs of arthritic changes (Fig 1A&B).

Figure 1A & B: The patient demonstrates moderate to severe hallux abductovalgus deformity. The apex of the deformity is at the level of the 1st metatarsal-cuneiform joint.

Plan: The decision was made to surgically repair the patient’s painful bunion deformity. Due to the severity of the deformity and the hypermobility present at the 1st metatarsal-cuneiform joint the procedure of choice was a Lapidus bunionectomy.

SURGICAL PROCEDURE

With the patient in the supine position, a 12cm longitudinal incision was made medial and parallel to the EHL tendon.  A standard lateral release was then performed. A periosteal and capsular incision was made, extending the entire length of the incision.  A laminar spreader was inserted into the 1st metatarsal-cuneiform joint for distraction and the joint surfaces were resected free of cartilage with an osteotome and curette. The subchondral plate was then drilled with a 2-0 drill bit and 3mm burr under copious irrigation. Care was taken to preserve the contour of the joints. The joint surfaces were apposed and the deformity was reduced with compression at the metatarsal heads. Temporary fixation was maintained with a .062 k-wire across the 1st & 2nd met heads with an additional k-wire across the metatarsal bases (Fig 2).

The joint was then fixated with a 3.5mm cortical screw placed in lag fashion across the joint from the central/lateral cuneiform into the 1st metatarsal base laterally. A 2nd 3.5mm cortical screw was then placed in lag fashion from the distal central metatarsal base into the medial cuneiform (Fig 3).

Figure 2: The k-wire across the metatarsal heads serves as primary temporary fixation. K-wires control rotation in order to preserve correction.	Figure 3: Fixation is achieved across the fusion site with crossing 3.5mm cortical screws inserted in standard lag fashion.

The correction was assessed and it was noted that there was instability at the level of the intercuneiform joint (Fig 4). Following temporary fixation with a 0.062 k-wire, a 3.5 cortical screw was then placed from the 1st metatarsal base transversely into the 2nd metatarsal base (Fig 5). The correction was again assessed and noted to be excellent. The remaining medial bone shelf at the level of the 1st metatarsal head was then resected. Final x-rays were then taken (Fig 6A&B). The wound was flushed and a layered closure was performed.

Post-operatively the patient remained NWB until osseous union of the arthrodesis site. The patient was placed on DVT prophylaxis for 4 weeks. The patient healed without incident and progressed to full weightbearing with a good functional outcome.

Figure 4: Under fluoroscopy, intercuneiform instability is assessed by attempting to manually abduct the 1st ray. Diastasis between the medial and intermediate cuneiform indicates the presence of instability at this level	Figure 5: The deformity is once again reduced and temporarily fixated. An additional 3.5mm cortical screw is then placed in lag fashion from the 1st metatarsal base laterally into the 2nd metatarsal base to address the instability.

Figure 6A & B: : Final post-operative x-rays reveal correction of both the inter-metatarsal angle and sesamoid position with elimination of the bunion deformity.

DISCUSSION

The Lapidus bunionectomy is a reliable and reproducible procedure for the correction of moderate to severe hallux abductovalgus deformity, especially in the presence of 1st metatarsal-cuneiform joint instability. Care must be taken to properly prepare the joint for fusion as well as temporarily fixate the position prior to insertion of permanent hardware. Contoured resection of the joint surfaces maintains a level of stability and more importantly, prevents excessive shortening of the first metatarsal, as seen with planal or wedge resection. Following fixation of the fusion site, it is imperative to test for intercuneiform instability. The most common cause of recurrence in these procedures is the failure to address proximal instability. In the presence of intercuneiform instability, fixation, or even fusion, of the medial column to the central column of the foot is recommended. This may be achieved with a diastasis screw, as in this case, or with fusion of either the 1-2 metatarsal bases or the intercuneiform joint. Following these guidelines, excellent correction of hallux abductovalgus deformity can be achieved and maintained longterm with the Lapidus bunionectomy.

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