Early mobilization after uncomplicated medial subtalar dislocation provides successful functional results

Management of StD requires immediate reduction under sedation to avoid soft-tissue and vascular complications [1]. Closed reduction is usually successful [1, 12, 13]. In nonreducible cases, however, multiple reduction attempts using force should not be undertaken, and open reduction should be performed without delay [6]. Frequently, associated lesions occur in the ankle and foot such as osteochondral fractures of the dislocated articular surfaces and fractures of neighboring bones (malleoli, the base of the fifth metatarsal, the cuboid, and the navicular tuberosities) [14]. If such concomitant injuries are suspected from routine radiological images, further investigation should be undertaken with computed tomography (CT) scan.

We believe that the prognosis of an isolated medial subtalar dislocation basically relies on three parameters: (1) immediate reduction (the necessity of which has already been underlined), (2) the amount of energy absorbed by the soft tissues at the moment of the violent impact, and (3) the period of postreduction immobilization.

The need for immediate reduction has already been discussed earlier. The mechanism of injury is an important factor in predicting long-term results. The results are worse after more violent mechanisms [14]. Simple inversion rarely produces dislocation with long-term morbidity, while more violent injuries, e.g., those incurred in motor vehicle accidents or after a fall from height, are more likely associated with persistent symptoms [14]. Concerning the immobilization period, previous studies have set the length of non-weight-bearing plaster use to 5 or 6 weeks [5, 6]. According to other researchers [7‐10], subtalar joint stiffness in uncomplicated StD can be minimized by avoiding immobilization longer than 4 weeks, or 6 weeks in case of StD associated with fractures. In general, the duration of postreduction immobilization is a controversial subject. Christiensen et al. [15] immobilized their patients in a long cast for 8 weeks after reduction of the dislocation. Twenty-one of their 30 patients faced pain when walking. Buckingham [16] reported on five patients, of whom four had decreased ROM following immobilization for 6 weeks. In other previous large series [5] of uncomplicated medial StD that incorporated immobilization for 5 weeks, subtalar joint ROM was decreased by 30–50% compared with the contralateral side and the tibiotalar ROM was moderately reduced. Moreover long immobilization has been correlated with high percentages of arthritis and decreased function rating between 50–80% [6, 15, 17]. McKeever [18], on the other hand, strongly encouraged measures to prevent fibrosis by early mobilization of the foot. He stated that, since the reduction of a subtalar dislocation is extremely stable, early mobilization is possible. He began ROM exercises, consisting of active assisted motion of the subtalar and midtarsal joints, after 3 weeks of immobilization. Of the eight patients he treated, five were immobilized for 3 weeks and had a normal range of subtalar motion and no complaint of pain. Forty-five years after McKeever’s study, our research confirms the advantages of early mobilization protocols for uncomplicated medial StD, using an even shorter period of immobilization than McKeever did.

The prospective nature of our study, which allowed for the use of a prespecified protocol, ensured better control of the patient cohort during the follow-up period and a more reliable survey of the protocol itself. The application of certain inclusion and exclusion criteria created a homogeneous group of patients (those who had sustained uncomplicated medial StD), excluding bias due to nonsimilar injury patterns. We preferred to focus solely on uncomplicated medial StD, since this is the most usual type of peritalar dislocation that a clinician may need to manage. Homogeneity was also ensured by the fact that all patients received the same reduction method, which consisted of manipulation under sedation. It should be noted that none of the patients needed to receive general anesthesia, as usually suggested in literature [1, 12, 13]. Sedation proved sufficient, allowing immediate reduction in the A & E department and saving valuable time that would be lost if the patient had to be transferred to theater and receive general anesthesia. Another strong point of our study was the existence of pre-assessed intervals for clinical and radiographic follow-up examination, which allowed for analogue timescale comparisons to be made. In contrast, the limited number of cases was a drawback of our research; this was expected, since subtalar dislocation is a rare injury. The small series of patients was the price to pay for the prospective character of the study. We believe, however, that it was worthwhile since the results, albeit from a small sample, were not controversial. Nonetheless, the study is still ongoing, thus further patients and results will be added in the future. Additional credibility could have been provided to the study if a control group of patients undergoing longer periods of immobilization had been included. The researchers were limited by two factors: the already mentioned small number of cases, and the ethical hesitation to provide patients with a type of treatment (long periods of immobilization) that we did not believe to be optimal.

Based on the aforementioned, it would be safe to say that our working hypothesis was confirmed: Early ankle ROM exercises and PWB mobilization after uncomplicated medial StD seem to provide better functional results than those achieved by longer periods of immobilization, as already mentioned in literature. As joint instability, following closed reduction of medial subtalar dislocation, is not a possible complication, protracted immobilization only adds to joint stiffness and minimizes ankle and foot functionality. In contrast, early active ROM exercises may help the ligaments and the tendons of the site to heal without compromising proprioception of the joint.

As basic practical recommendations extracted from this study, we could state the following: (a) immediate closed reduction should be applied in the case of any kind of StD, (b) sedation of the patient is usually sufficient for reduction of uncomplicated medial StD, (c) time-consuming general anesthesia should be used only in case of irreducible closed StD requiring open surgical reduction procedures, and (d) early mobilization protocols are indicated as beneficial for ankle and foot functionality after medial uncomplicated StD. Continuation of this study will add further credibility to its usefulness. Nonetheless, for definite results to be drawn, multicenter clinical trials will be required, and the creation of collaborative databanks of patients between multiple centers and countries may be necessary.