Abstract
Background: Tibialis anterior tendon (TAT) rupture is an uncommon injury, however, it can cause substantial deficit. Diagnosis is often delayed due to lack of initial symptoms; yet loss of function over time typically causes the patient to present for treatment. This delay usually ends up with major defects creating a great technical challenge for the operating surgeon. We present a novel technique and operative algorithm for the management of chronic TAT ruptures with a major gap after a delayed diagnosis not otherwise correctable with currently described techniques in the literature. This technique has been performed in 4 cases without any complications with fairly successful functional outcomes. Methods: For the reconstruction of chronic TAT rupture with an average delay of nine weeks after initial injury and gap of greater than 10 cm, a thorough operative algorithm was implemented in 4 patients using a double bundle gracilis allograft. Patients were then kept nonweightbearing for 6 weeks followed by weightbearing as tolerated. They began physical therapy with a focus on ankle exercises and gradual return to normal activity at 8 weeks, with resistance training exercises allowed at 12 weeks. Results: At a mean follow-up time of 24.5 months, all patients reported significant pain relief with normal gait pattern. There were no reported intra- or postoperative complications. The average Foot and Ankle Ability Measure score increased to 90 from 27.5 in the postoperative period. All patients were able to return their previous activity levels. Conclusions: Gracilis allograft reconstruction as used in this study is a viable and reproducible alternative to primary repair with postoperative results being favorable without using complex tendon transfer techniques or autograft use necessitating the functional sacrifice of transferred or excised tendon. To the best of our knowledge, this is the first study demonstrating a successful technique and operative algorithm of gracilis allograft reconstruction of the TAT with a substantial deficit of greater than 10 cm with favorable results.
Rupture of tibialis anterior tendon (TAT) can be very debilitating due to reduced strength of ankle dorsiflexion and its effect on gait. 1 Traumatic tendon rupture often occurs following rapid plantar flexion and eversion of a dorsiflexed ankle but oftentimes patients are unaware of a traumatic incident and search treatment after they feel the functional loss or discover a lump on the dorsum of their foot or ankle.1,2 TAT is the third most ruptured tendon in the lower limb and strongest of the 3 ankle dorsiflexors, yet this injury has the propensity to go undiagnosed for many months.3,4 In a study including 12 patients TAT rupture, only 2 patients sought immediate medical attention. 5 This delay may be due to the lack of external signs of rupture such as a hematoma formation or swelling. 6 Negative sequelae of a TAT rupture include drop foot, claw toes, and progressive flattening of the arch.1,4,5,7,8
Treatment recommendations for chronic rupture include bracing, orthotics, and strengthening exercises, especially in a lower activity level group. Surgical options include tenoplasty, repair, or when primary repair is not possible, reconstruction. Reconstruction by sliding TAT lengthening or tendon turndown, tendon transfer or free autograft tendon transfers have been previously described.9-11 Although autograft techniques using extensor hallusis longus, peroneus brevis, or hamstring tendons have been reported to have satisfactory results, all of them carry the risk of donor site morbidity and resulting functional loss. 12 In the setting of a chronic deficiency of greater than 4 cm, allograft tendon repair has been shown to be beneficial. 8 We present a near anatomic reconstruction technique of a chronic rupture of TAT with a substantial defect greater than 10 cm using a double bundle gracilis allograft, a tendon that has been shown to be very good for extensor tendon reconstructions due to the quality and diameter of the allograft. 13 To our knowledge, no study has examined the effectiveness of a gracilis allograft or reconstruction of a defect greater than 10 cm for the repair of a chronic TAT rupture.
Materials and Methods
This study was approved by the institutional review board (IRB number: MODCR00000855). TAT reconstructions using gracilis allograft were performed on 4 patients by the senior author who is a fellowship trained foot and ankle orthopedic surgeon. There were 2 male patients and 2 female patients. The primary diagnosis was TAT rupture with a delayed diagnosis of an average of 8.75 weeks (range 3-12 weeks) postinjury or first presentation. There were no concomitant injuries and all ruptures were unilateral. All patients had the chief complaints of slapping gate pattern and catching of the floor due to drop foot. They were also complaining of weakness and slow walking pace.
On physical examination, all patients had a palpable defect at the TAT trace with loss of dorsiflexion strength and a slapping gate. Mean age at time of surgery was 70 years (range 57-81 years). All patients had preoperative magnetic resonance imaging done confirming healthy anterior tibial muscle belly with no fatty infiltration. The average tendon defect size was measured 11.5 cm intraoperatively (range 10-13 cm). Operative technique, which is described below, was used for the reconstruction. Foot and Ankle Ability Measure (FAAM) was used to determine preoperative and postoperative foot and ankle functional outcome.
Operative Technique
Chronic TAT rupture with a major gap was reconstructed in the following order:
Skin incision is made along the ruptured TAT trace
Ruptured tendon edges are exposed and debridement is performed
Proximal tenolysis is performed and proximal stump is tensioned
Length of the final defect is measured
Appropriate length allograft is chosen and tensioned
Bone tunnel is created in the medial cuneiform in dorsolateral to plantar medial direction
Allograft is sutured to the proximal stump using pulvertaft technique
Allograft is passed through the bone tunnel
Distal end of the allograft is sutured to the proximal stump
Surgery was performed under general anesthesia and a single shot popliteal block with an indwelling nerve catheter. The patient was positioned supine and a bump was placed under the ipsilateral hip to place the foot in neutral position. The operation was done under thigh tourniquette (Figure 1).
Operative Algorithm.
We used an incision that began 2 to 3 cm proximal to the extensor retinaculum, going down to the insertion of TAT on the medial cuneiform. An extensive incision has been chosen to be able to retrieve the proximal stump by opening the extensor retinaculum, which was always found at the proximal extensor retinaculum level, and release its adhesions to the retinaculum and other surrounding soft tissues. In all the reported cases, the senior attending surgeon started with a less extensive incision at the distal end of the extensor retinaculum but could not reach or mobilize the proximal stump without extending the incision proximally and opening the retinaculum. Extensor retinaculum was released and dissection was carried down to TAT sheath and the tendon was usually found thickened and degenerated with no actual viable tendon tissue inside the sheath (Figure 2A). We then released and tensioned the proximal tendon stump as it was always found to have lost its excursion and to obtain maximum length. The defect was then measured. We then calculated the appropriate gracilis allograft length by doubling the defect size and adding 2 cm on both ends for the tunnel and pulvertaft suture. A bone tunnel was then created on the medial cuneiform starting from dorsal-medial to plantar-lateral direction mimicking the natural TAT insertion under fluoroscopy guidance (Figures 2A and 3). The allograft was then sutured to the proximal stump using pulvertaft technique and passed through the bone tunnel in the same direction, as we have created (Figures 2B and 4). The distal stump was then turned and sutured back to itself and the proximal stump creating a double bundle affect at the TAT insertion site mimicking the normal anatomy (Figures 2C and 5). The extensor retinaculum and soft tissues were then closed and patient was placed in a 3-sided coaptation splint in neutral dorsiflexion. Patient was kept nonweight bearing until the first 3-week follow-up clinic visit.
(A) Schematic drawing of the operative technique showing tibialis anterior tendon (TAT) defect, suturing of the allograft to the proximal stump using pulvertaft technique, and bone tunnel placement. (B) Schematic drawing showing passage of the allograft through the bone tunnel. (C) Schematic drawing of final position of the double bundle allograft.
Intraoperative image showing the tibialis anterior tendon (TAT) defect, notice the fraying dejenerated edges of the proximal stump
Intraoperative image showing gracilis allograft sutured to the proximal stump using pulvertaft technique.
Intraoperative image showing final position of the allograft and tunnel placement.
Postoperative Management
All patients returned for their first postoperative visit in 3 weeks for a wound check and suture removal. At this time they were placed back in a Cam boot in neutral position and remained nonweightbearing for an additional 3 weeks, after which they were allowed to begin weightbearing gradually starting with 25% of their body weight and returned to full weightbearing status in 4 weeks. Formal physical therapy sessions were advised at that time to regain range of motion and strength. Resistance training exercises were allowed at 12 weeks and the repair was protected using over the counter ankle braces for 6 months.
Results
This technique has been performed in 4 cases by the senior author from 2008 to 2012. All patients healed without any immediate or late complications, including neurovascular damage or perioperative infection. All 4 patients showed improved function at a mean follow-up time of 24.5 months (range 24-25 months). All patients reported complete recovery and that they would have the same surgery again if they are asked. The average preoperative FAAM score increased from 27.5 (range 18-34) to 90 (range 84-98) postoperatively, yielding an average increase of 62.5. All patients returned to same preoperative activity level at the last follow-up visit. All patients had same ankle range of motion and muscle strength compared with the contralateral unaffected ankle without any slapping gate pattern (Table 1). One patient developed a loss of motor function at the end of our follow-up period due to new onset axonal peripheral polyneuropathy affecting the operated foot.
Patients’ Info and Demographics.
Abbreviations: FAAM, Foot and Ankle Ability Measure; ROM, range of motion.
Discussion
Bruning first described TAT rupture in 1905, which is an uncommon yet debilitating injury. The majority of the literature on the topic being in the form of case reports, literature reviews, and small case series.2,3,8,14-17 Diagnosis may be delayed due to the ability to dorsiflex the ankle being maintained, especially in low-demand patients. Previous literature has described 2 mechanisms of injury for a TAT rupture. The first involving an atraumatic rupture in a low-demand elderly individual that can go unnoticed for an extended period of time and often requires conservative treatment. The second involves a traumatic event, typically in a higher functioning individual that involves a noticeable pre- and postinjury functional difference. 5
Definitive treatment of these continues to be controversial. Conservative treatment is an option and typically described for elderly, low-demand individuals. Two studies have shown that there are significant deformities associated with the long-term nonoperative management of TAT rupture, including persistent foot drop, claw toes, pain, and neuroma formation.1,5 Sammarco et al 18 published one of the largest case series of 19 cases of closed ruptures of TAT, 3 of which were traumatic ruptures, all treated surgically with promising results. We believe that in order to restore preinjury level of function, surgical reconstruction is necessary, especially in the latter population. Before deciding on operative treatment, the individual expectations with regard to sport activity and profession of the patient should be considered. If possible, tendon suture repair or distal avulsion reattachment with transosseus tunneling can be done for primary repair in anatomic fashion. In defects up to 4 cm, sliding tendon lengthening may be performed or alternatively an augmented tenoplasty (longitudinal tendon preparation that will be turned down to cover the defect) is recommended. If the gap is larger than 4 cm, tendon grafting or transfer may be done. 11 The largest tendon gap that was treated surgically using an auto or allograft in the literature is 9 cm. 9
Substitution of the extensor hallucis longus, extensor digitorum longus, the extensor of the fifth toe, the peroneus brevis or tertius, and the posterior tibial tendon have also been reported. However, autograft use has been shown to alter the normal functional anatomy of foot and ankle and increase morbidity by changing the normal foot and ankle kinematics, increasing the operative time or number of incisions, causing stress fractures or decreased range of motion in the postoperative period.15,17 Grundy et al 19 reported that half of the patients who received EHL transfer for operative treatment of TAT rupture developed symptomatic hallux interphalangeal joint extensor lag in the postoperative period.
There has been a recent trend toward using free tendon allografts in the interposition of major defects of TAT ruptures due to potential morbidity associated with tendon transfers. Huh et al 20 have shown that surgical correction of the chronic tibialis anterior tendon rupture with appreciable tendon defect can be repairable with intercalary allograft with satisfactory results. In their study, distal allograft stump was fixed to the navicular using an interference screw, different from our double bundle bone tunnel technique which requires no hardware for fixation, thus decreasing the overall cost of the operation. To our knowledge, there are no published data on the treatment of TAT rupture with a major defect (more than 10 cm) with the use of gracilis allograft.
Diagnosis in our 4-patient sample was made an average of 9 weeks after injury; we did have substantial tendon deficit and retraction due to the chronicity of the injury thus supporting the need to surgically correct these injuries within 3 months to avoid further negative sequelae. 21 Diagnosis of a TAT rupture was supported by physical examination findings of a pseudotumor at the anteromedial ankle, loss of normal contour of the TAT, and recruitment of the extensor hallucis longus and extensor digitorum longus for ankle dorsiflexion. 22 It is vital to have a good physical examination, including testing the extensor hallucis longus and extensor digitorum longus to isolate the location of the injury. None of our patients presented with a chief complaint of pain, they were active individuals that noticed a deficit in their ability to dorsiflex at the ankle thus making them a good surgical candidate. In a patient leading an active lifestyle, we recommend operative management be pursued if diagnosed within three months of rupture as supported by Dooley et al. 16
Based on the results of the described 4 cases, we conclude that TAT reconstruction using a gracilis allograft is a safe, cost-effective, and viable option, especially in cases with a major defect. Previous literature has advocated for conservative management of TAT ruptures, especially in low-demand patients. 15 However, in patients that have an active and healthy lifestyle, this procedure allows patients to resume their previous level of activity and also reduces the comorbidities associated with chronic rupture.
Taking these factors into consideration during surgical intervention, successful outcomes were seen with our subjects. Given the rarity of the injury and our limited number of patients, we are unable to make firm treatment recommendations. Rather, we are able to provide a comprehensive surgical algorithm for consideration in patients who present with delayed TAT rupture with a major defect.