Proximal tibiofibular dislocation: a case report and review of literature

An isolated dislocation of the proximal tibiofibular joint is uncommon. The mechanism of this injury is usually sports related. We present a case where initial X-rays did not show the tibiofibular joint dislocation conclusively. It was diagnosed after comparative bilateral AP X-rays of the knees were obtained. A closed reduction was performed and followed by unrestricted mobilization after 1 week of rest. A review of the literature was conducted on PubMed MEDLINE. Thirty cases of isolated acute proximal tibiofibular joint dislocations were identified in a search from 1974. The most common direction of the dislocation was anterolateral, and common causes were sports injury or high velocity accident related. More than 75 % of the cases were successfully treated by closed reduction. Complaints, if any, at the last follow-up (averaging 10 months, range 0–108) were, in the worst cases, pain during sporting activities. We advise comparative knee X-rays if there is a presentation of lateral knee pain after injury and diagnosis is uncertain. Closed reduction is usually successful if a dislocation of the proximal tibiofibular joint is diagnosed. There is no standard for after-care, but early mobilization appears safe if there are no other knee injuries.


Introduction
The proximal tibiofibular joint facilitates only a little movement with some rotation to accommodate the rotational stress at the ankle joint during dorsiflexion [1]. Isolated dislocation of the proximal tibiofibular joint was first described by Nelaton in 1874 [2]. A dislocation of the proximal tibiofibular joint is uncommon and accounts for \1 % of all knee injuries. It is a mostly sports related [3]. The diagnosis is easily missed on plain AP X-rays of the knee, and bilateral AP X-rays are helpful to identify a proximal tibiofibular dislocation [4]. We describe a case of a proximal anterolateral tibiofibular joint dislocation treated at our facility and include a short review of current literature, published after the classic paper on this condition by Ogden in 1974 [5].

Case report
A 31-year-old male patient presented to our A&E department after sustaining a knee injury during soccer. The exact mechanism could not be elucidated, but the pain started after landing on his right foot after an air challenge. He was unable to bear weight on his right leg. On physical examination, there was a diffuse and discreet swelling on the lateral side of the right knee and local pain on palpation (Fig. 1). Flexion and extension were possible but painful after 110°of flexion on the lateral side of the knee. The knee was stable to stress examination of the ligaments. There was no distal neurovascular deficit.
An AP and lateral X-ray of the knee showed no evident pathology on first assessment (Fig. 2). Diagnosis was made after additional AP X-rays of both knees were obtained. This showed a dislocated proximal tibiofibular joint on the right side (Fig. 3). The fibula was dislocated in an anterolateral direction.
A reduction was performed after administering fentanyl and midazolam, with the knee flexed at 90°and the foot in external rotation and eversion, administering direct local pressure using a thumb in the sulcus between the fibula and tibia on the anterior side. Pressure was directed laterally on this location and resulted in a marked pop and instant pain relief for the patient (Fig. 4). Control X-rays showed a reduced proximal tibiofibular joint (Fig. 5).
A three-layer pressure bandage for 1 week and early mobilization was permitted. Further follow-up was uneventful. After 6 weeks, the patient started participating fully in sports. At final follow-up at 6 months, the patient was without any complaints.

Discussion
The proximal tibiofibular joint is a small joint with minimal movement. The classic paper on proximal tibiofibular    Bilateral AP X-ray of the knees. The aberrant position of the proximal fibula on the right side is evident when compared to the left knee. The direction of the luxation is anterolateral dislocation and subluxation by Ogden from 1974 describes four types of instability: atraumatic subluxation, posteromedial dislocation, anterolateral dislocation and superior dislocation. This last type is rare. The most common direction of dislocation is anterolateral in which the mechanism most often involves a violent, twisting motion. This mechanism is commonly seen in various sports, especially during landing after jumping or evading an opponent in team sport [1,5].
The typical clinical presentation is pain located on the lateral side of the knee after a sports injury. This can be confused easily with a lateral meniscal lesion, especially if guarding because of pain is mistaken for restricted range of motion from a displaced meniscal tear. After establishing the diagnosis, the peroneal nerve should be examined and any changes in sensation noted [1,5].
In case of an inconclusive diagnosis, plain X-rays of the affected knee in two planes and comparative X-rays of the asymptomatic knee should be taken or, occasionally, an MRI or CT obtained [6].
The reduction should be performed with the knee flexed 90°-110°and externally rotating the foot and applying direct pressure over the fibular head [5,7].
The most common cause for dislocation of the proximal tibiofibular joint were sports related or from a high-velocity accident. The direction of dislocation reported was almost exclusively anterolateral. In two cases, the direction of dislocation was not specified [9,12]. In seven cases (23 %), an open reduction was performed [3, 8-10, 18, 24, 25]. All other cases were reduced in a closed manner, three (10 %) of these were spontaneous reductions [9,10,15].
The reported after-treatment following a closed reduction was mixed. It ranged from no specific instruction to 6 weeks of immobilization in a long leg cast. The followup was 10 months on average (range 0-108). Problems reported on follow-up were occasional aches or pain during sports. But most of the patients did not have residual complaints.
The stated reason for an open reduction was a failed closed reduction, but no explanation was provided as to why the closed reduction had failed. An open reduction was always followed by a fixation; this varied from temporary to definitive fixation, but from the identified papers, we were unable to discern an implant of choice for this fixation.

Conclusion
We advocate comparative knee X-rays for patients presenting with lateral knee pain after a sports injury for which a diagnosis is not reached from clinical examination or a single set of X-rays. If diagnosed, an attempt at closed reduction is recommended. There is no evidence for the restriction of weight bearing or immobilization after a successful closed reduction. Early movement and weight bearing protected by elbow crutches in the first week is a Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.