1.1 Patients

The present study included patients with¹ acetabular fracture treated at a Level 1 Trauma Center between January 2009 and December 2020. Eligible patients were identified from the pelvic registry,² provided informed consent, and³ were of working age (18–65 years) at the time of trauma.

1.2 Material und methods

Data on postal dispatch, socio-demographics, epidemiological classification, injury type, and accident date were obtained from the Level 1 Trauma Center pelvic registry. Acetabular fractures were classified according to Letournel, individual injury severity by the AIS, and overall severity by the ISS.¹²

A rating system developed at the University of California, Los Angeles (UCLA Activity Score) was used to define the highest activity level pre-trauma (PRE) and post-trauma (POST). The scale ranged from 1 = completely inactive to 10 = vigorous physical work or contact sports.¹³ The questionnaire assessed sport aspects, including activity level, training frequency and duration, impact level, painkiller use during sport, and POST sport breaks and changes in sport. The term “painkiller” was not further specified and was interpreted individually by participants.¹⁴

Finally, participants reported how their subjective attitude toward exercise had changed due to the trauma.

1.3 Data collection and analysis

The study population was contacted by post in October 2021 with an information letter, consent form, and questionnaire containing retrospective patient-reported outcome measures (PROMs). Completed questionnaire and consent form were returned by mail, missing data were clarified by telephone. All consenting patients were evaluated pseudonymously. No physical examinations, imaging, or personal contact occurred.

Data analysis was purely descriptive, as the cohort comprised only 22 patients and subgroup sizes were too small for adequately powered statistical testing.

The study was reviewed by the local ethics committee (project no. 760/2021BO2), which raised no objections.

2.1 Participants

A total of 544 patients were recorded in the pelvic registry during the study period (396 pelvic ring-, 149 acetabular fractures). Addresses were available for 290 patients, including 56 eligible acetabular fracture cases.

Fifteen patients could not be contacted, and one patient was deceased, leaving 40 questionnaires successfully mailed. Fourteen patients did not respond despite repeated contact attempts, and four declined participations. Thus, 22 fully completed questionnaires were available for evaluation. (response rate 22/40 = 55 %) (Fig. 1).

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Fig. 1 Flowchart of participants.

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We included 7 women (31.8 %) and 15 men (68.2 %) with a median age at the time of trauma of 45 (IQR 33.5–54.75) years. The median time between trauma and sending the questionnaire was 145.0 (IQR 75.5–166) months.

2.2 Injury and rehabilitation

There were 15 elementary fractures (68.2 %) and 7 combined patterns (31.8 %) according to Letournel. Based on the AIS, 16 patients (72.7 %) had an AIS 3 injury; 4 of them (18.2 %) sustained an additional Tile B pelvic ring injury. Six patients (27.3 %) had an AIS 4 injury with a concomitant Tile C pelvic ring fracture. In total, 10/22 patients (45.5 %) had an associated pelvic ring injury.

According to the ISS, 14/22 (63.6 %) were classified as polytrauma and 8/22 (36.4 %) as non-polytrauma. The mean ISS of the entire cohort was 23.4 ± 15.0 (range 9–59). Mean ISS was 9.8 ± 1.5 (range 9–13) in the non-polytrauma subgroup and 31.2 ± 13.5 (range 17–59) in the polytrauma subgroup.

Polytrauma patients more frequently underwent inpatient rehabilitation, while non-polytrauma patients more often participated in outpatient programs. Subgroup details are shown in Table 1.

2.3 Maximum performance

Overall, the highest UCAL Activity Score declined markedly after acetabular fractures. Both subgroups demonstrated a reduction, which was more pronounced in patients without polytrauma. Detailed results are presented in Tables 2 and 3.

2.4 Return to sport

Of the patients with pre-trauma sporting activity, 81.3 % (13/16) returned to sport, while 18.8 % (3/16) did not. Return rates differed between subgroups: 50 % (3/6) in the non-polytrauma group versus 100 % (10/10) in the polytrauma group (Fig. 2).

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Fig. 2 shows the sport activity (y-axis: number of patients; x-axis: answer in questionnaire): Most patients were engaged in sports prior to the fracture. Among those previously active, return-to-sport rates were lower in the non-polytrauma subgroup, whereas all polytrauma patients resumed sport POST.

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The POST sports break was markedly longer in the polytrauma subgroup (median 459 days, IQR 135.5–730) than in the non-polytrauma subgroup (median 90 days, IQR 0). Sporting activity levels declined in both groups (Table 4).

Before injury, polytrauma patients more often participated in club sports, whereas non-polytrauma patients mainly performed casual activities. POST, both groups reduced activity level and intensity, with a more marked decline in the non-polytrauma subgroup. Non-polytrauma patients trained less frequently but longer PRE, and more frequently but shorter POST, resulting in a major net reduction. Polytrauma patients showed only moderate decreases, and both groups largely discontinued high-impact sports. (Table 4).

Use of pain medication during activity increased in both subgroups. Most non-polytrauma patients who had trained without analgesics required pain medication POST, whereas polytrauma patients—despite increased analgesic use—more often continued exercising without pain medication.

2.5 Subjective attitude towards sporting activity

Overall, most patients (59 %; 13/22) reported no change in their general attitude towards sporting activity. In the ‘non-polytrauma’ subgroup, attitudes towards sporting activity were largely stable, with only few positive or negative shifts. In contrast, half of the patients in the ‘polytrauma’ subgroup reported no change, while negative shifts in attitude were more frequent than positive ones (Fig. 3).

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Fig. 3 shows change the subjective attitude towards sporting activity: Most patients in the ‘no polytrauma’ subgroup reported no change, while in the polytrauma subgroup negative shifts in attitude were more common.

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3.1 Return to sport and maximum performance

Almost 20 % of the cohort did not resume sporting activity after an acetabular fracture.

The subgroup analysis shows that patients with polytrauma are more likely to resume sporting activity than those without polytrauma. The contrast between the subgroups was striking: patients without polytrauma returned to sport earlier, but fewer of them resumed sporting activity and at a lower activity level. Rehabilitation was undertaken less frequently in this subgroup. In contrast, all patients in the ‘polytrauma’ subgroup eventually returned to sport after a longer interruption, underwent more frequently inpatient rehabilitation and reached higher activity level compared to the ‘no polytrauma’ subgroup. In line with this, Yabroudi et al. (2021) demonstrated that a longer rehabilitation period (≥4 months) was positively correlated with return to sport after anterior cruciate ligament surgery, which could help explain the findings of the present study.¹⁵

Patients in the polytrauma subgroup showed higher activity levels and more frequent sporting activity both before and after trauma, suggesting that sport played a more prominent role in their daily lives.

Our study is the first to characterize pre- and post-traumatic physical activity in patients with acetabular fractures.

3.2 Painkiller consumption on return to sport

Following acetabular fractures, painkiller use during sporting activity increased, particularly in the ‘polytrauma’ subgroup. This corresponds with Monteleone et al. (2023), who identified postoperative pain as the major limitation after acetabular fractures.¹⁶

3.3 Subjective attitude towards sporting activity

Most patients reported no change in their subjective attitude toward sporting activity, although a relevant share described a negative shift. This was more frequent and predominantly negative in the polytrauma subgroup, while attitudes in the non-polytrauma subgroup remained largely stable. To our knowledge, this is the first study to examine attitude changes toward sport after acetabular fracture.

Physical activity is associated with numerous benefits, including reduced depression, pain, blood pressure, and cognitive decline, as well as improved self-esteem and quality of life.^5,17,18 Conversely, depression can reduce activity levels.¹⁹ Moreover, subjective sport perception strongly influences participation, with positive attitudes promoting and negative attitudes limiting performance.⁷

A negative attitude toward exercise may contribute to lower activity levels and adverse biopsychosocial outcomes. In this study, a notable proportion of patients showed a negative shift in attitude; however, this did not parallel the UCLA Activity Score. Although activity decreased more in the non-polytrauma subgroup, negative attitude changes were more common in polytrauma patients. Further factors such as motivation, reasons for attitude changes, and subjective experience during activity should be explored, particularly as sport played a greater role pre- and post-trauma in the polytrauma subgroup.