September 14, 2018
7 min read
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A 15-year-old patient with right ankle pain, difficulty walking uphill

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A 15-year-old male patient presented with difficulty walking uphill during the past 2.5 years due to involuntary flexion of the first, second and third toes of his right foot and limited ankle dorsiflexion. He reported difficulty with other movements that require maximal ankle dorsiflexion, including deep squats. He had mild discomfort with these movements and noted bothersome callus formation occurred over the dorsal interphalangeal joint of the hallux and the distal plantar aspect of the first three toes. He had not received any treatment. The patient has a history of a right triplane ankle fracture with an associated fibula fracture that occurred approximately 3 years prior. At the time of injury, he underwent internal fixation through a medial approach to the tibia and lateral approach to the fibula.

On physical exam, there was a well-healed scar over the medial aspect of the right tibia and lateral aspect of the fibula. Gait was observed with an abnormal terminal stance phase prior to push-off due to clawing of the first three digits and relatively restricted right ankle dorsiflexion. No hindfoot abnormality was appreciated. Active range of motion was mildly limited in dorsiflexion. Flexion contracture of the interphalangeal joints of the first, second and third digits was seen with the right ankle in a plantigrade position that worsened with further ankle dorsiflexion to 5° and returned to neutral with plantar flexion (Figure 1). Click here to watch a video demonstrating the involuntary flexion.

Flexion contracture of the first three toes
Figure 1. Neutral position of the toes with right ankle in plantar flexion is shown (a). Flexion contracture of the first three toes is seen with the right ankle in dorsiflexion (b). A frontal view of the right ankle in dorsiflexion demonstrates flexion contracture that involves the first three toes (c).
Figure 2. Lateral radiograph of the right ankle and two views of the right foot demonstrate internal fixation of the tibia and fibula. Flexion of the first three digits can also be seen.

Source: Rajeev D. Puri, MD

Plain radiographs demonstrated healed fractures of the right tibia and fibula with plate fixation (Figure 2). No hardware failure was appreciated.

What is your diagnosis?

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Checkrein deformity of the right foot involving the first three toes

Clinical examination demonstrates a checkrein deformity of the right foot involving the first three toes. A checkrein deformity is a dynamic flexion contracture of the interphalangeal joints of the hallux and lesser toes due to tethering of the flexor hallucis longus (FHL), which is exaggerated with ankle dorsiflexion and reduces with plantar flexion.

The delayed development of this pathology after the patient’s history of triplane and fibular fracture after internal fixation points to an etiology of FHL tethering due to adhesions at the posterior distal tibia where the prior injury occurred. This tethering of the FHL creates an exaggerated tenodesis effect at the ankle, which gives rise to the characteristic increase in deformity with ankle dorsiflexion and resolution with plantar flexion. The corresponding manifestations in the second and third digit arise due to tendinous tethers between the FHL and flexor digitorum longus (FDL) tendons distally.

Treatment

No clinical improvement was seen with conservative management, which included physical therapy. Surgical correction of the deformity by lengthening the FHL tendon and possible tenotomy of the flexor tendons to the lesser toes was discussed with the patient. He and his parents/guardians confirmed they understood the risks and benefits of the procedure and elected to proceed with this surgical intervention.

Intraoperatively, step-cut lengthening of the FHL
Figure 3. Intraoperative exposure and isolation of the FHL tendon at the midfoot is shown.
Figure 4. Intraoperatively, step-cut lengthening of the FHL tendon is performed (a) in two steps (b).
Figure 5. Intraoperative range of motion testing demonstrates resolution of the checkrein deformity.
Figure 6. Postoperative range of motion testing is shown in plantar flexion (a) and dorsiflexion (b), which demonstrates the patient has no recurrence of the checkrein deformity.

A medial approach to the midfoot was used to gain access to the FHL tendon at the level of the Knot of Henry and careful dissection was performed to isolate the FHL tendon away from the FDL tendon (Figure 3). Step-cut lengthening of the FHL tendon was performed (Figure 4). Intraoperative ankle range of motion testing was conducted and complete resolution of the dynamic flexion contracture of the hallux was appreciated. However, a mild flexion contracture remained in the second and third toes when the ankle was in maximal dorsiflexion, so percutaneous tenotomy of the flexor tendons was performed at the level of each respective proximal phalanx. Ankle range of motion was repeated, and complete correction of the deformity was obtained (Figure 5). All wounds were closed, and the patient was placed in a splint with his ankle in a neutral position. He was instructed to remain non-weight-bearing.

Postoperatively, the patient returned for wound check at week 2 at which time no recurrence of deformity was seen (Figure 6). He was placed in a CAM boot and remained non-weight-bearing for an additional 4 weeks. The patient returned for his 4-month follow-up at which time he was doing well. He had resolution of symptoms without recurrence. There was no extensor drift seen on exam of the lesser toes.

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Discussion

Checkrein deformity is a rare condition that can result from trauma of the lower extremity, which results in entrapment of the FHL. The FHL becomes tethered and creates a dynamic flexion contracture of the hallux. The lesser toes can be involved due to the tendinous interconnections between the FHL and FDL. The deformity worsens with ankle dorsiflexion and often resolves with plantar flexion. Fixed deformities have been reported. The checkrein deformity most commonly occurs following tibia and fibula fractures; however, talar fractures and calcaneus fractures have also been implicated.

The checkrein deformity can be immediately present at the time of trauma. Reports demonstrate it is a result of FHL entrapment within fracture fragments and resolves with proper release of the FHL during fracture reduction and fixation. On the other hand, checkrein deformity can have a delayed development seen months after the initial trauma, such as in the case presented. In these cases, the entrapment and tethering of the FHL was due to adhesions at the site of bone healing.

Multiple treatments have been reported to correct delayed checkrein deformity. In case reports reviewed in the literature, there was no success with conservative management. Many surgical strategies have been used, which can be conceptually divided into those that address the deformity proximal or distal to the ankle joint.

The proximal approach typically uses a posteromedial incision of the lower leg and direct release of the FHL by lysis of adhesions and resection of bony infiltrates at the site of pathology. However, this often requires a relatively large dissection and may not provide satisfactory results. Yuen and colleagues required additional release of the FHL tendon at the midfoot to resolve the deformity despite performing a proximal release using a posteromedial approach. In addition, recurrence of the deformity using the proximal treatment approach may be an area of concern as higher recurrence rates have been reported. To address the large surgical dissection, Lui described success with a proximal endoscopic adhesiolysis of the FHL.

The distal approach to treatment typically involves FHL tendon lengthening at the level of the midfoot, which bypasses the pathology by lengthening the FHL downstream from the adhesions. This provides a less extensive surgical dissection with satisfactory results and there have been no reports of recurrence in the literature reviewed. Despite promising results, questions exist regarding whether the strength of the muscle is preserved, as it remains tethered proximally and muscle fiber excursion may be lost. However, loss of active hallux flexion has been observed in patients who underwent the proximal or the distal approach.

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Treatment of flexion deformity of the lesser toes can be achieved with either surgical approach. Release of adhesions using the proximal approach removes tethering of the FHL and releases the FDL through tendinous interconnections. In the distal treatment approach, direct disruption of these interconnections can result in deformity correction. Variable anatomy of the interconnections may cause difficulty and contribute to the incomplete resolution of lesser toe deformity with the distal approach. As in the case presented, percutaneous tenotomy of the flexor tendons can be performed to complete the correction.

The checkrein deformity is a dynamic flexion contracture of the hallux due to tethering of the FHL after traumatic injury to the lower leg and often involves the lesser toes. It characteristically worsens with ankle dorsiflexion and resolves with plantarflexion. This condition can be managed either with proximal release of adhesions at the posterior tibia and fibula or distal FHL tendon lengthening at the midfoot. We prefer the distal treatment approach because it involves a smaller surgical dissection and appears to have lower recurrence rates compared with the proximal approach.

Disclosures: Lee reports he is a board or committee member of the American Orthopaedic Foot & Ankle Society; member of the editorial or governing board of Foot and Ankle International; and receives publishing royalties, financial or material support from SLACK Incorporated. Bohl, Hur and Puri report no relevant financial disclosures.