Traumatic hip dislocation has become increasingly common in recent decades due to the rise in road traffic accidents. It accounts for 5% of all dislocations [1], and accidents are responsible for more than 60% of hip dislocations [2][3]. It can be accompanied by other injuries such as fractures, thoracoabdominal and spinal injuries, which are life-threatening if not treated promptly [2]. Diagnosis is most often clinical; an anteroposterior and lateral pelvic X-ray is necessary and mandatory in any suspected dislocation to confirm the diagnosis [3]. Diagnosis is sometimes difficult, especially in the context of polytrauma [4].

It is an absolute medical emergency that can compromise the functional prognosis of the hip, hence the need for rapid reduction after its occurrence [5]. Complications are not negligible and are dominated by the risk of post-traumatic osteoarthritis and necrosis of the femoral head [1].

Given the high incidence of road traffic accidents and the lack of precise data on hip dislocations in our region, we deemed it useful to conduct this study. The objective was to describe the epidemiological, clinical, therapeutic, and prognostic aspects of traumatic hip dislocations in the orthopedic and trauma surgery department of the University Hospital Center of N’Djamena (CHU-RN).

This was a single-center, retrospective, cross-sectional study conducted from January 2017 to December 31, 2022 (5 years) in the orthopedic and trauma surgery department of the CHU-RN in N’Djamena. This study included all patient records of those with radiographically confirmed acetabular-femoral dislocation who were treated and followed up in the department during the study period. Records of patients discharged against medical advice and incomplete records were excluded. The variables studied were epidemiological (age, sex, occupation), clinical (etiological circumstances, mechanism, functional signs, classification, associated injuries), therapeutic (reduction method, time to treatment), and outcome (functional result according to Postel and Merle d’Aubigné and complications).

Data were collected using a pre-established individual questionnaire and the department’s hospitalization and outpatient records, as well as the operative reports and nurses’ on-call logs. Anatomopathological analysis was performed on radiographic and sometimes CT scans, and the lesions were classified according to Bigelow [6]. The functional outcome was assessed according to the Postel and Merle d’Aubigné score (PMA) [7] (the outcome is said to be excellent when PMA is 18, very good PMA 17, good PMA 15 - 16, passable PMA 13 - 14, poor PMA 9 - 12 and mediocre PMA < 9) with a minimum follow-up of 18 months. Data were analyzed using Epi Info 7 software. Results were presented in tables, figures, and text. They were expressed as percentages and absolute numbers.

During the study period, 44 hip dislocation cases were identified, including 6 cases of discharge against medical advice, 2 unusable cases, and 36 cases of traumatic hip dislocations meeting our criteria out of 1996 cases of admission to the department, representing a hospital frequency of 1.8%. Males predominated with 25 cases (69.4%), and the male-to-female ratio was 2.27. The mean age was 30 years, ranging from 18 to 47 years, with a predominance of patients in the 18 - 23 age group. Table 1 shows the distribution of patients according to occupation and etiological circumstances, and Table 2 shows the clinical characteristics. The dislocations were recent in 30 cases (83%) and old in 6 cases (17%). Emergency orthopedic reduction by external manipulation was performed in 30 patients (83%). Surgical treatment was performed in 10 patients (28%). These included one case of open reduction after failed orthopedic treatment, six cases of open reduction for old dislocations, and three cases of acetabular osteosynthesis for fracture-dislocations. Table 3 summarizes the management of associated injuries. At a mean follow-up of 18 months, the outcome was favorable in 30 cases (83%). We observed 4 cases of coxarthrosis and 2 cases of osteonecrosis of the femoral head. The overall clinical and functional results according to the PMA score are summarized in Table 4.

Table 1. Distribution of patients according to occupation and etiological circumstances.

Table 2. Clinical characteristics.

Table 3. Distribution of patients according to the treatment of associated injuries.

Table 4. Overall functional outcomes according to the PMA score.

Over a 6-year period, we collected 36 cases of traumatic hip dislocations out of 1996 admissions, representing a frequency of 1.8%, with an average of 6 cases per year. This frequency is similar to that reported by Akobé [8], who found a rate of 1.7% in his study. Discharges against medical advice in favor of traditional treatment could explain this frequency, which appears to be underestimated. Our study shows that traumatic hip dislocations are more common in young males, who are more active and therefore more exposed to various types of trauma. The same observation is made in the work of several authors [8]-[11]. The socio-professional class varies from one series to another, but victims are often involved in road traffic accidents. In our series, dislocations affected several socio-professional classes, with a predominance of students followed by motorcycle taxi drivers. Akobe et al. [8] report the predominance of traders. All the socio-professional groups mentioned are very active and, in most cases, use two-wheeled vehicles for transportation, exposing them to road traffic accidents. Regarding the etiological circumstances, road traffic accidents were the cause of traumatic hip dislocations in 78% of cases in our study, as described in the literature [9]-[12]. The predominance of road traffic accidents in the circumstances of occurrence could be due to the growth in the number of cars and two-wheeled vehicles, and to non-compliance with vehicle inspection standards and the highway code. As for the clinical varieties, high posterior (iliac) dislocations were the most frequent, 92%, consistent with data from other authors [11][13][14]. This anatomical and clinical presentation can be explained by the dashboard mechanism, often observed in road traffic accidents. Indeed, this region is characterized by a predominance of muscle mass and a weakness of the ligamentous apparatus.

Associated lesions were observed in 14 patients (38.8%), with 16 lesions, and these were dominated by acetabular fractures, occurring in 9 cases (25%). Akobe et al. [8] found a similar result. Since the acetabulum is the bone in direct contact with the femoral head, it is easier to understand why it is the first to fracture during violent displacement of the latter. This supports the hypothesis that traumatic hip dislocations are caused by high-energy trauma dominated by the dashboard mechanism. Dislocations were reduced in the emergency department under general anesthesia by external manipulation in 30 cases (83%). In the literature, this treatment method is more commonly used in cases of traumatic dislocation. Surgical treatment was indicated for irreducible traumatic hip dislocations and hip fracture-dislocations, as described in several series in the literature [15]. Thus, open reduction was performed on one patient after failure of orthopedic treatment and three fracture-dislocations with osteosynthesis of the acetabulum. Six old dislocations (five iliac, one obturator) also underwent open reduction with unsatisfactory results upon evaluation. The treatment of choice for neglected hip dislocations is total hip arthroplasty [16][17], but our patients, often with a low socioeconomic status and no health insurance, cannot afford the cost of these prostheses.

At a mean follow-up of 18 months, we recorded two cases of osteonecrosis of the hip joint and four cases of coxarthrosis. Garret et al. [18] found 11 cases of femoral head necrosis after a follow-up period ranging from 1 to 8 years for irreducible dislocations. Other studies have shown that the number of necrosis cases increases with follow-up [19][20].

Hip dislocation is a common trauma emergency. Its frequency is constantly increasing in our setting due to urbanization and the motorization of transportation, constituting a genuine public health problem. Iliac dislocation was the most frequent. It was most often associated with an acetabular fracture. When reduced urgently or as soon as possible, hip dislocations have good outcomes. However, osteoarthritis of the hip remains the most frequently observed complication. The only truly effective treatment lies in the prevention of road traffic accidents.

Conceptualization, Andjeffa Valentin and Adendjingue Daniel Mossalbaye; methodology, Andjeffa Valentin; software, Andjeffa Valentin; validation, Andjeffa Valentin, Adoum Allamine, and Larguet Djimet Hiby Lantar1; formal analysis, Andjeffa Valentin; investigation, Minguemadji Service; resources, Medilla Moussa Ali; data curation, Andjeffa Valentin; writing—original draft preparation, Andjeffa Valentin; writing—review and editing, Andjeffa Valentin; visualization, Dingamnodji Magloire; supervision, Daffe Mohamed; project administration, Andjeffa Valentin; funding acquisition, Adendjingue Daniel Mossalbaye. All authors have read and agreed to the published version of the manuscript.