Traumatic Hallux Varus in Association with Agenesis of the Fibular Sesamoid: A Case Study

A 52-year-old woman presented to our office approximately 9 months after injuring her right foot. Her medical history was significant only for a motor vehicle accident in 1993 in which she sustained a pelvic fracture, right ankle fracture, luxated right patella, and lacerations of the right femoral artery and quadriceps. These injuries required orthopedic and reconstructive surgery. She states that she was gardening while wearing flip-flops when her foot fell into a hole. She said it felt as if her foot and toe went one way and the shoe went another direction. Pain was noted initially but her foot did not appear dramatically different at the time. Over the course of 9 months, she noted that her great toe gradually rotated medially. She began to experience increased difficulty getting into shoes and discomfort when wearing shoes. By the time she presented to our office, her great toe was in notable varus deformity, which increased in severity with weightbearing. Radiographs were taken and a varus deformity was confirmed with a 21° varus hallux abductus angle but, interestingly, absence of the fibular sesamoid was also apparent (Fig. 1A). On physical examination, she did have some discomfort with dorsiflexion, without a notable decrease in range of motion. Contralateral radiographs were also obtained and, again, the fibular sesamoid was absent. There was also a 5° varus deformity of the left foot detected by means of weightbearing radiographs that was not apparent clinically (Fig. 1B). She denied ever having surgery to either foot. Treatment options were discussed, but the patient wished to avoid surgery. A trial of taping the toe was unsuccessful. At her next follow-up, again surgical options were discussed and it was advised that a fusion of the first metatarsophalangeal joint (MPJ) would be the most reliable procedure. Soft-tissue repair procedures were also explained, and she was cautioned that they are sometimes not successful and recurrence of the deformity is possible. She had previously been in a motor vehicle accident in 1993 and endured serious injuries, leaving her more proximal lower extremity joints with limited range of motion. She was concerned that fusing the first MPJ would lead to a serious hindrance on her ability to get up from a sitting position and potentially a hindrance on her independence. She was therefore not interested in a fusion. A magnetic resonance imaging scan was later obtained and demonstrated that the adductor tendon appeared to be intact, but also demonstrated heterogeneity of the tendon, indicating injury. The lateral collateral ligament was noted to be disrupted. Medial displacement of the proximal phalanx and varus subluxation of the MPJ were also apparent (Fig. 1C). Axial views demonstrated, again, absence of the fibular sesamoid (Fig. 1D and E). After discussing the MRI results, the patient opted for soft-tissue repair.

The patient was seen in the office approximately 22 months postoperatively and stated that she had experienced nearly no pain since her operation other than when the Kirschner wire advanced into her foot. She now has no pain and states that she often forgets that there was once an issue with her foot. She is now to the point that she can wear high heels all day without issue. She does relate some tightness in the joint, especially when bending to pick something up, but states this does not affect her activities. She does relate that there is loss of plantar flexion strength but that this does not impact her activities. Overall, she is very happy with her progress following the procedure. On physical examination, her correction has been maintained as evidenced by weightbearing and nonweightbearing photographs (Fig 3 A and B). Postoperatively, she can achieve approximately 30° of dorsiflexion compared to 45° in the left foot (Fig. 3C). Weightbearing radiographs of the right foot were taken at 22 months postoperatively and demonstrate maintenance of correction, but with development of arthritis in the first MPJ (Fig. 4 A–C). Her hallux abductus angle measures 9° valgus compared with her preoperative hallux abductus angle of 21° of varus. This demonstrates a maintained reduction of 30°.

In this case, it is postulated that the function of the adductor hallucis and lateral capsular ligaments were destroyed during the minor accident. This likely would have allowed the abductor hallucis tendon and medial capsule to have greater pull on the proximal phalanx. We believe that lack of the fibular sesamoid contributed to the cause of the injury in much the same way that excision of the sesamoid can lead to hallux varus. In this case, the sesamoid complex was inherently weak laterally because of the absence of the fibular sesamoid. The traumatic event in our case would have likely been a relatively low-velocity trauma, whereas many of the case studies identified for this article are much more high-velocity–type injuries. This supports our theory that lack of the fibular sesamoid was largely a contributing factor to the severity of her injury in that the lateral capsular ligaments are weakened by the lack of fibular sesamoid. This is supported by her slight varus on the left foot without injury. Jahss also described a case of a patient who presented with hallux varus and was noted to have absent fibular sesamoids.[7] This patient did not undergo trauma and was asymptomatic.

After a thorough literature review, there are many studies on iatrogenic hallux varus, but there are few studies on traumatic hallux varus. Each of these studies involves a similar mechanism of injury, and we believe our case is unique in that congenital absence of the sesamoid in conjunction with a traumatic event led to symptomatic hallux varus with a less forceful traumatic event. There have been several different methods of soft-tissue repair proposed, all of which involved some form of soft-tissue augmentation and tendinous procedures. We performed a repair using an EHL split tendon transfer as described by Gradsiek and Weil.[9,10] Our procedure differed in that we added a medial capsulotomy and lateral capsulorraphy and maintained our correction with a temporary Kirschner wire across the first MPJ. Gradsiek and Weil described a postoperative course of nonweightbearing or protected weightbearing for 6 weeks and physical therapy at 1 week. We placed our patient nonweightbearing for 2 weeks with protected weightbearing the following 4 weeks. At 2 months, she transitioned to an athletic shoe. We did not deem physical therapy necessary. Twenty-two–month follow-up demonstrated that our repair was stable, and she remains pain-free in regular shoe gear. This repair adequately recreates the lateral capsular ligaments and the pull of the adductors and balances the pull of the abductor hallucis tendon.

Although iatrogenic hallux varus is well known and the subject of ample publications, traumatic hallux varus is rarely reported. To our knowledge, this is the first publication of traumatic hallux varus in a patient with congenital absence of the bilateral fibular sesamoids. In most cases of traumatic hallux varus, there was a relatively forceful action leading to the eventual development of varus. In our case, the traumatic event was relatively minor. This leads us to conclude that lack of the fibular sesamoid predisposed her to this type of injury through a weakened lateral capsule. This theory is supported by an anatomical and clinical study of hallux varus by Joseph et al, who concluded that disruption of the lateral stabilizers can lead to hallux varus.[6] Our chosen procedure allowed reconstruction of the adductor tendon while still leaving the insertion of the extensor hallucis longus and its function intact. We believe this approach provided a stable reconstruction while still allowing the range of motion she needed to retain her mobility. A weakness of the procedure is that the temporary Kirschner wire became too close to the skin to remain in place without discomfort. This wire could have been cut longer or gauze could have been placed between the skin and wire to prevent discomfort. This did not seem to detract much from the case, as her correction has maintained over 22 months. A weakness of this study is that it is a case review. A formal study with multiple patient cases, either prospective or retrospective, would be more powerful.