Doctor, When Should I Start Walking? Revisiting Postoperative Rehabilitation and Weight-Bearing Protocols in Operatively Treated Acetabular Fractures: A Systematic Review and Meta-Analysis

Background and Objectives: Management of acetabular fractures is aimed at anatomically reducing and fixing all displaced or unstable fractures, as the accuracy of fracture reduction has been demonstrated to strongly correlate with clinical outcomes. However, there is a noticeable gap in the literature concerning the perioperative and postoperative care of patients with acetabular fractures, which ultimately can be potential risk factors for adverse outcomes and permanent disabilities. This study aimed to systematically review the available literature regarding rehabilitation practices, including weight-bearing protocols, across time points in surgically treated acetabular fracture patients and correlate these practices with functional outcomes. Methods: We systematically reviewed the Medline and PubMed databases and the Cochrane Central Register of Controlled Trials in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The inclusion criteria were studies with adult patients (19+ years), publications from the last 10 years, articles focusing on rehabilitation or mentioning any aspect related to rehabilitation (such as weight-bearing or muscle training), and describing the surgical management of acute, isolated acetabulum fractures. Specific information was collected, including the fracture classification, time to surgery, surgical approach, surgical time, blood loss, fixation strategy, quality of reduction, postoperative rehabilitation protocol, complication rate, type(s) of complication, and outcome measurement(s). The choice(s) of surgical approach, surgical time, blood loss, and fixation strategy were stratified based on the fracture classification. The complication rate and type(s) of complication were calculated for all studies. Fractures were classified based on the Letournel classification. Results: A total of 494 articles were identified from the initial search, of which 22 (1025 patients) were included in the final review. The most common rehabilitation protocol favored isometric quadriceps and abductor strengthening exercises starting on the first postoperative day, with passive hip movement at 1–3 days postoperatively and active hip movement ranging from the first postoperative day to 4 weeks postoperatively. Partial weight-bearing with a walker or a pair of crutches was permitted from 1 to 12 weeks after surgery, and full weight-bearing was allowed depending on the patient’s general condition and fracture healing state (generally at the end of 3 months). In only three studies did the patients start bearing weight in the early postoperative period (≤1 week). Meta-regression analysis was not performed due to the discrepancy between studies that reported a weight-bearing protocol ≤1 week and >1 week postoperatively. Conclusions: Our study suggests that an accelerated postoperative rehabilitation protocol, including early permissive weight-bearing, does not appear to increase the risk of loss of reduction or the rate of complications after surgical treatment of acetabular fractures. However, a proper meta-analysis was not possible, and the heterogeneity of the included studies did not allow us to conclude anything about the potential biomechanical and clinical benefits nor the negative effects related to this rehabilitation regimen in terms of functional results. There is an inconsistent use of PROMs for objectively calculating the effect size of the accelerated protocol compared with restricted weight-bearing regimes. We pose the need for higher-level evidence to proof our hypothesis.


Introduction
The management of acetabular fractures is aimed at anatomically reducing and fixing all displaced or unstable fractures, as the accuracy of the fracture reduction has been demonstrated to strongly correlate with clinical outcomes [1,2].Following these fundamental principles, historically good-to-excellent functional outcomes have been reported in up to 80% of operatively treated patients [1,3,4].However, it has been pointed out that overall, studies lack high-quality data on medium-and long-term functional follow-ups, which can theoretically bias the existing reported outcome [5].In addition, notable changes in several aspects of acetabular fractures have been occurring, as patients are getting older and sustaining different spectra of fracture patterns [5].
At present, understanding the fracture classification, performing a proper exposure, achieving an anatomic reduction, understanding screw trajectories, and assessing intraand postoperative reduction are still the mainstays of acetabular fracture surgical management [2,5].While considerable attention has been dedicated to enhancing surgical skills and techniques, as well as identifying potential risk factors for adverse outcomes and permanent disabilities, there remains a noticeable gap in the literature concerning the perioperative and postoperative care of patients with acetabular fractures.
In this scenario, evaluating the effect of modifiers on perioperative and postoperative care, such as rehabilitation protocols and programs, seems to be essential to have a coherent sense of their impact on surgical outcomes.Rehabilitation of operatively treated orthopedic trauma patients has been demonstrated to be an integral part of the management, providing optimal care to injured patients [6,7].Specifically, in elderly patients with hip fractures, proper rehabilitation after surgery has been shown to shorten hospital stays, improve physical function, help patients maintain independent daily lives, and reduce the burden of medical treatment [8][9][10].
Our hypothesis is that standardized protocols for rehabilitation and weight-bearing restrictions following operative treatment of acetabular fractures are scarce in the literature.This gap in standardized protocols poses a challenge for orthopedic trauma surgeons and physical therapists aiming to optimize patient outcomes and ensure consistent quality of care.Addressing this issue is crucial for developing evidence-based guidelines for conducting rehabilitation efforts and weight-bearing protocols, ultimately improving the overall management of acetabular fractures and enhancing patient recovery.The aim of this systematic review and meta-analysis is to identify previously described rehabilitation practices, including weight-bearing protocols, across time points in surgically treated acetabular fracture patients and correlate these practices with functional outcomes.

Materials and Methods
This study was designed and conducted according to the guidelines proposed by the Cochrane Handbook for Systematic Reviews of Interventions (http://handbook-5-1. cochrane.org,accessed on 2 January 2024), and it was reported in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines [11].As this study was based on previously published studies, ethical approval and patient consent were not needed.

Search Strategy
A systematic review was performed using Medline and PubMed databases, as well as the Cochrane Central Register of Controlled Trials between August and December 2023, focusing on acetabular fracture rehabilitation and treatment outcomes.Searches were limited to human studies and the English language.The terms acetabulum fracture and rehabilitation were explored to obtain related search terms and categories using databaseappropriate search terms (Figure 1).
Cochrane Handbook for Systematic Reviews of Interventions (h p://handbook-5-1.cochrane.org,accessed on 2 January 2024), and it was reported in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines [11].As this study was based on previously published studies, ethical approval and patient consent were not needed.

Search Strategy
A systematic review was performed using Medline and PubMed databases, as well as the Cochrane Central Register of Controlled Trials between August and December 2023, focusing on acetabular fracture rehabilitation and treatment outcomes.Searches were limited to human studies and the English language.The terms acetabulum fracture and rehabilitation were explored to obtain related search terms and categories using databaseappropriate search terms (Figure 1).The inclusion criteria were adult patients (19+ years), publications from the last 10 years, articles focusing on rehabilitation or mentioning any aspect related to rehabilitation (such as weight-bearing or muscle training), and describing the surgical management of acute, isolated acetabulum fractures.The exclusion criteria were pathological fractures, acetabular fractures treated primarily with joint replacement, failure to inform about the follow-up period, nonexistence of evaluation criteria, experimental studies involving animals, cadaveric specimens, or biomechanical testing, review articles, case reports and small case series (<10 cases), expert opinions, and le ers to the editor.

Study Selection
Based on the titles and abstracts, three investigators (V.G., L.P.G.d.F., and T.M.) picked out the potential eligible studies.All duplicate titles were removed.Then, the full text of the remaining studies was reviewed for eligibility by the same three investigators, and any disagreements were resolved by discussions involving the other authors for the final decision.All studies were independently assessed to check whether they met the inclusion criteria.Again, if there was a disagreement regarding inclusion, it was resolved by a discussion involving the other authors for the final decision, and if no consensus could be reached, then the study was excluded.

Data Extraction and Outcome Measures
After full-text articles were selected, two investigators (V.G. and L.P.G.d.F.) independently performed data extraction and evaluated the quality of the included studies using the Methodological Index for Non-Randomized Studies (MINORS) criteria, a valid instrument designed to assess the methodological quality of non-randomized surgical The inclusion criteria were adult patients (19+ years), publications from the last 10 years, articles focusing on rehabilitation or mentioning any aspect related to rehabilitation (such as weight-bearing or muscle training), and describing the surgical management of acute, isolated acetabulum fractures.The exclusion criteria were pathological fractures, acetabular fractures treated primarily with joint replacement, failure to inform about the follow-up period, nonexistence of evaluation criteria, experimental studies involving animals, cadaveric specimens, or biomechanical testing, review articles, case reports and small case series (<10 cases), expert opinions, and letters to the editor.

Study Selection
Based on the titles and abstracts, three investigators (V.G., L.P.G.d.F., and T.M.) picked out the potential eligible studies.All duplicate titles were removed.Then, the full text of the remaining studies was reviewed for eligibility by the same three investigators, and any disagreements were resolved by discussions involving the other authors for the final decision.All studies were independently assessed to check whether they met the inclusion criteria.Again, if there was a disagreement regarding inclusion, it was resolved by a discussion involving the other authors for the final decision, and if no consensus could be reached, then the study was excluded.

Data Extraction and Outcome Measures
After full-text articles were selected, two investigators (V.G. and L.P.G.d.F.) independently performed data extraction and evaluated the quality of the included studies using the Methodological Index for Non-Randomized Studies (MINORS) criteria, a valid instrument designed to assess the methodological quality of non-randomized surgical studies, whether comparative or non-comparative [12].Basic information was collected, including the journal name, author(s), year published, level of evidence, number of fractures, and follow-ups.Specific information was collected, including the fracture classification, time to surgery, surgical approach, surgical time, blood loss, fixation strategy, quality of reduction, postoperative rehabilitation protocol, complication rate, type of complication(s), and outcome measurement(s).The choice of surgical approach(es), surgical time, blood loss, and fixation strategy were stratified based on the fracture classification.The complication rate and type(s) of complication were calculated for all studies.Fractures were classified based on the Letournel classification [13,14].
A full narrative synthesis of the included studies was conducted, focusing on correlating the outcome measurements with the postoperative weight-bearing regimen.When possible, quantitative synthesis was undertaken for the postoperative outcome measurements to compare between non-weight-bearing and weight-bearing postoperative regimens and determine the difference in functional outcomes between groups.In cases with no comparison between groups in terms of weight-bearing regimens, single-arm meta-analysis was undertaken to pool the results of the single-arm observational studies and assess the overall outcome measurement.All relevant information from each article was extracted and inserted into an Excel document.

Assessment of the Risk of Bias
Initially, each primary study was assessed based on its OCEBM level of evidence (LoE) [15].The potential presence of publication bias was first explored visually by generating the respective funnel plots for the main outcomes of interest.A symmetrical distribution of the studies about the pooled effect estimate would be interpreted as an absence of publication bias.Furthermore, we utilised Egger's test and Begg's rank test.For both tests, there is an indication of publication bias when the two-sided p value is extremely low (below the significance level).Sensitivity analysis was performed by repeating the pooling process after eliminating studies of either a low methodological rating with the MINORS criteria or dubious eligibility [12].Should this process not yield considerably different results than the ones originally obtained, our confidence surrounding the robustness of our findings would increase.The risk of bias was assessed using the Cochrane robvis visualization tool and evaluated according to the Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I) tool for studies that were not randomized [16].

Statistical Analysis
Data were extracted and entered into an Excel spreadsheet.Statistical analysis was carried out to estimate the overall event rate using Comprehensive Meta-Analysis software (version 2.0; Biostat, Inc., Englewood, NJ, USA).The Yates-corrected chi-squared test was used to assess categorical variables, and the Kruskal-Wallis test was used for independent measures.After this, the Shapiro-Wilk test was used preliminarily to test the normality and homogeneity of the variables assessed.A p value <0.05 was considered significant.

Selection of Studies
A total of 494 records were identified through database searches.After screening titles and abstracts and removing duplicates, 86 potentially relevant records met our eligibility criteria, and full-text articles were selected.Of these, 64 records were discarded, leaving 22 records (1025 patients) that were included in the final review.The search strategy for databases with a flowchart of the literature selection process is outlined in Figure 2.

Characteristics of the Studies
All studies included in the final analysis were either individual cohort studies (n = 3), representing a grade of recommendation of B and level of evidence of 2b, or low-quality cohort or case-control studies (n = 19), representing a grade of recommendation of C and level of evidence of four .All studies were assessed using the MINORS criteria, which contain 12 items, with the first eight being specifically for non-comparative studies, giving a maximum score of 16 for non-comparative studies and 24 for comparative studies.The maximum score indicates that methodological items were adequately reported.The mean score was 12.8 (range: 9-15) for non-comparative studies and 19.5 (range: 18-21) for comparative studies.Unbiased assessment of the study's endpoint and lack of prospective calculation of the study size were the main problems encountered in the noncomparative studies, whereas unbiased assessment of the study's endpoint, lack of prospective calculation of the study size, and inadequate statistical analyses were the main problems of the comparative studies.Most studies were published in 2014 (n = 6), 2017 (n = 4), and 2018 (n = 4).Six studies were published in Injury (Elsevier Ltd. (Amsterdam, The Netherlands); 2022 Journal Impact Factor: 2.9; 2022 Journal Citation Indicator (JCI): 0.850) [20,23,25,28,29,33] [18,24].The characteristics of the included studies are presented in Table 1.The risk of bias is shown in Figure 3 [16].

Characteristics of the Studies
All studies included in the final analysis were either individual cohort studies (n = 3), representing a grade of recommendation of B and level of evidence of 2b, or low-quality cohort or case-control studies (n = 19), representing a grade of recommendation of C and level of evidence of four .All studies were assessed using the MINORS criteria, which contain 12 items, with the first eight being specifically for non-comparative studies, giving a maximum score of 16 for non-comparative studies and 24 for comparative studies.The maximum score indicates that methodological items were adequately reported.The mean score was 12.8 (range: 9-15) for non-comparative studies and 19.5 (range: 18-21) for comparative studies.Unbiased assessment of the study's endpoint and lack of prospective calculation of the study size were the main problems encountered in the non-comparative studies, whereas unbiased assessment of the study's endpoint, lack of prospective calculation of the study size, and inadequate statistical analyses were the main problems of the comparative studies.Most studies were published in 2014 (n = 6), 2017 (n = 4), and 2018 (n = 4).Six studies were published in Injury (Elsevier Ltd. (Amsterdam, The Netherlands); 2022 Journal Impact Factor: 2.9; 2022 Journal Citation Indicator (JCI): 0.850) [20,23,25,28,29,33] [18,24].The characteristics of the included studies are presented in Table 1.The risk of bias is shown in Figure 3 [16].
The mean blood loss for the patients operated on through the Kocher-Langenbeck approach was 483.8 ± 232.9 mL, with a mean surgical time of 135.3 ± 12.2 min [28,32,38].The mean blood loss for the patients operated on through the ilioinguinal approach was 793 ± 228 mL, with a mean surgical time of 182 ± 40 min [17].The mean blood loss for the patients operated on through the lateral-rectus approach was 440 ± 153 mL, with a mean surgical time of 75 ± 29 min [21].Due to the small sample size, no correlation was possible between the surgical approach, mean blood loss, and mean surgical time.Seventeen studies mentioned the type of implant used for fracture fixation, which varied from conventional non-locked implants (3.5 mm reconstruction plates, one-third tubular plates, small fragment cortical and cancellous screws, large fragment cancellous screws, cables, and 7.3 cannulated screws) to locked implants (3.5 mm reconstruction plates and screws and precontoured anatomical plates) [17,[19][20][21][22][23][24][25][26][28][29][30][31][32][33]35,36,38].The perioperative parameters and form of treatment of the included studies are presented in Table 3.

Postoperative Rehabilitation Protocol
A range of postoperative rehabilitation protocols was described in the 22 included studies according to timing, range of motion, muscle training, and weight-bearing .Overall, isometric quadriceps-and abductor-strengthening exercises were started on the first postoperative day, with passive hip movement at 1-3 days postoperatively and active hip movement ranging from the first postoperative day to 4 weeks postoperatively.Partial weight-bearing with a walker or a pair of crutches was permitted from 1 to 12 weeks after surgery, and full weight-bearing was allowed depending on the patient's general condition and fracture healing state, generally at the end of 3 months.A faster weight-bearing protocol was performed by Schwabe et al. [35], who utilized a supervised mobilization regimen with 30 kg of weight-bearing on the ipsilateral extremity with crutches or a mobile walking device, which started on the first day after the operation, and full weight-bearing after 6 weeks postoperatively.On the contrary, more prolonged weight-bearing protocols were described by Kizkapan et al. [26] and Maini et al. [32], with patients being allowed to perform partial weight-bearing 3 months after surgery and start full weight-bearing between 4 and 6 months after surgery.
Postoperative skeletal traction was described in three studies [20,32,38].Fahmy et al. [20] kept their patients on absolute bed rest with continuous transtibial traction for 6 weeks and started passive mobilization of the operated hip after the 10th postoperative day.Maini et al. [32] used skeletal traction for 3 weeks followed by a non-weight bearing status for 6-12 weeks, depending on the stability and fixation of the joint.Finally, Yang et al. [38] maintained skeletal traction for 2-4 weeks in patients with traumatic posterior hip dislocation before starting functional hip exercise.
Follow-ups ranged from 6 weeks to 9 years.The quality of reduction, postoperative rehabilitation protocol, and outcome measurements of the included studies are presented in Table 4.The follow-up periods and complications are outlined in Table 5.   Skeletal traction for 3 weeks, non-weight-bearing status for 6-12 weeks, depending on stability and fixation of the joint, and full weight-bearing after 12-20 weeks.
Extremely good in 6 cases, good in 13 cases, medium in 2 cases, and fair in 1 case Schwabe, P. et al. [33] Anatomic in all cases Supervised mobilization with 30 kg of weight-bearing on the ipsilateral extremity with crutches or a mobile walking device started during the first day after the operation, with full weight-bearing after 6 weeks postoperatively.
Excellent in 8 patients and good in 4 patients (HHS) Li, H. et al. [26] Excellent in 45 cases, good in 10 cases, and fair in 2 cases Joint exercise recommended as tolerated by pain, activities limited for an average of 12 weeks before partial weight-bearing was permitted, depending on the fracture stability, and full weight-bearing only after confirmed clinical and radiological fracture union.
Excellent or extremely good in 45 cases, good in 8 cases, fair in 2 cases, and poor in 2 cases Uchida, K. et al. [35] Anatomic in 42 cases, satisfactory in 27 cases, and unsatisfactory in 2 cases Patients enrolled in physical therapy program on the third postoperative day, starting with hip (affected side) abduction and flexion, followed by isometric and then isotonic exercise, allowing sitting from 1 week and walking using a single cane without orthosis from 10 weeks.

Meta-Analytic Regression
The only study to assess non-weight-bearing versus weight-bearing regimens did not report any outcome evaluation score.In a therapeutic retrospective cohort study with 137 patients with displaced acetabular fractures that underwent ORIF, it was observed that loss of reduction (increase of >2 mm in either the articular step or gap) due to early weight-bearing presented a relative risk of 1.506 (CI: 0.503-4.514),with no significant difference between the two groups (p = 0.664) [27].In two other studies, patients started weight-bearing in the early postoperative period (≤1 week).In a retrospective case series with 22 consecutive patients submitted to three-dimensional fluoroscopy-navigated percutaneous screw fixation of minimally displaced acetabular fractures, there was no complication, with excellent results in eight patients and good results in four patients based on the HHS system [35].All patients underwent supervised mobilization with 30 kg of weight-bearing on the ipsilateral extremity with crutches or a mobile walking device starting on the first postoperative day, and full weight-bearing was permitted after 6 weeks postoperatively.In a retrospective study of prospectively collected data from 25 patients with displaced acetabular fractures treated by ORIF using the Kocher-Langenbeck approach along with trochanteric flip osteotomy, excellent-to-good results were observed in 22 (88.0%)cases [22].All patients were allowed to perform toe-touch weight-bearing within the first week, and full weight-bearing was permitted at the end of 3 months.There were three complications, none of which were related to the weight-bearing regimen.In the remaining studies, partial weight-bearing was permitted after at least 4 weeks after surgery, showing high overall heterogeneity.A bubble plot of the functional outcome (mean MDPS and mean HHS) versus weight-bearing time (early (≤1 week) and delayed (>1 week)) was established (Figures 4 and 5), but meta-regression analysis was not performed due to the discrepancy between studies that reported a weight-bearing protocol ≤1 week and >1 week postoperatively.Because some of the included studies did not report the mean scores, the mean values within the MDPS (excellent = 18, good = 16, fair = 13, and poor = 7 points) and the HHS (excellent = 95, good = 85.regular = 75 and poor = 35 points) were adopted for the purpose of calculating the averages.For this calculation, the study by Hammad et al. was excluded [23].

Discussion
Our study demonstrated scarce evidence when comparing the relationship between the postoperative rehabilitation protocols, especially weight-bearing, and the most commonly used patient-reported outcome measure scores for patients treated surgically for acetabular fractures.Although the outcome measures were described in 19 of the 22 included studies [17][18][19][20][21][22][23]25,26,[28][29][30][31][32][33][34][35][36]38], meta-regression analysis was not possible due to discrepancies between studies, especially in relation to weight-bearing protocols ≤1 week and >1 week postoperatively.Of the 15 studies in which the authors used the modified Merle D'Aubigné and Postel score included in the meta-regression analysis, in only one were patients encouraged to perform an early weight-bearing protocol [17][18][19][20][21][22]25,26,28,30,31,[34][35][36]38].The same was observed in the six studies in which the authors used the Harris hip score, where only one described an early weight-bearing protocol [18,19,29,[33][34][35].The reason why restricted or limited delayed weight-bearing after acetabular fracture fixation is preferred among surgeons is unclear, as most orthopedic surgeons routinely prescribe at least partial weight-bearing for a lower extremity fracture in an attempt to produce an optimal mechanical environment at various stages of fracture healing [41].From a biomechanical point of view, weight-bearing produces micromovements between the fracture fragments, stimulating bone consolidation, which clinically implies rapid functional recovery and a faster return to activities of daily living, thus potentially reducing complications associated with late rehabilitation protocols [42,43].
The management of acetabular fractures should be aimed at anatomical reduction and stable fixation of all displaced or unstable fractures, thus enabling early patient rehabilitation [2].However, the literature on weight-bearing status after fixation of an acetabulum fractures continues to empirically suggest at least 6 weeks of non-weight-bearing as the most prevalent postoperative treatment option, mainly due to fear of implant failure, fracture displacement, and loss of reduction.This more conservative recommendation appears to be motivated by the belief that by reducing the forces acting at the fracture site, the bone and ligament healing processes will occur without greater risk of fixation failure [42][43][44].In fact, in the 22 studies included , we consistently observed that active and passive hip movements and isometric quadriceps-and abductor-strengthening exercises were started between one and three days postoperatively, and weight bearing was basically postponed depending on the patient's general condition and fracture healing state.Interestingly, non-weight bearing has been shown to be associated with greater energy expenditure and higher contact pressures at the hip joint, with peak pressures in the acetabulum during sitting and standing activities performed during restricted weight-bearing being nearly three times the forces observed during walking [42,43,45,46].Moreover, much of the force during sitting and standing activities is directed posteriorly, whereas during ambulation, more load is distributed to the upper lateral surface of the roof [42,45,46].
Although it is well recognized that the quality of reduction remains the most important factor for a better functional outcome, other factors have been identified as also affecting the functional recovery of the hip after an acetabular fracture, including the patient's involvement in the rehabilitation protocol [47].In this scenario, addressing the issue of rehabilitation after surgical treatment of acetabular fractures gains importance, especially when some authors have not reported loss of reduction or an increase in complications when allowing early permissive partial weight-bearing, even after percutaneous fixations using screws only [22,27,35,43,48].Kojima et al. [27] showed that different weight-bearing regimes (early vs. late) did not influence the quality of reduction in 137 patients with surgically treated displaced acetabular fractures.Schwabe et al. [35] found no complications in 22 consecutive patients submitted to percutaneous screw fixation of minimally displaced acetabular fractures, who utilized a supervised mobilization weight-bearing regimen which started on the first day after the operation and full weight-bearing after 6 weeks postoperatively.Similarly, Kazemi and Archdeacon [48] found no loss of reduction and observed similar results in 22 patients who underwent percutaneous fixation with screws and were allowed immediate full weight-bearing postoperatively.Not surprisingly, the benefits observed from faster recovery in the immediate postoperative period, including early permissive weight-bearing, have shown similar results and complications in other articular fractures of the lower limbs [49][50][51][52].
Another aspect that must be taken into consideration and that is constantly neglected in the description of the follow-up after fixation of an acetabulum fracture is the low adherence of patients to medical restrictions regarding weight-bearing in the postoperative period.Chiodo et al. [53] measured the compliance with a period of prescribed non-weightbearing in 51 consecutive adult orthopedic patients with unilateral lower-extremity injuries or procedures.The noncompliance rate with the postoperative non-weight-bearing restriction was 27.5%, despite explicit instructions and education about possible complications associated with weight-bearing.No significant influence on weight-bearing performance was found regarding sex, age, language spoken, body mass index, time in a cast, or the treating surgeon.Braun et al. [42] continuously monitored 10 patients after surgical treatment of an acetabulum fracture with a pressure-measuring insole.In the postoperative protocol, the authors instructed every patient to maintain a 20 kg weight-bearing limit for 6 weeks, but only one patient stayed within the weight-bearing limit during the analysis.Despite almost all patients exceeding the prescribed amount of weight-bearing, the postoperative reduction was maintained at the 6 week timepoint, suggesting that higher plantar loading has no effect on the early radiographic results [42].
When bringing together all the pros and cons of reported rehabilitation protocols, it seems that immediate or early weight-bearing may not place patients at an excessive risk of displacement after fixation of an acetabulum fracture.Although the quality of reduction and fixation techniques remains the most important factor in obtaining satisfactory outcomes after surgical treatment of acetabular fractures, our study highlights the need to review current postoperative weight-bearing protocols.The ability to walk has been shown to be an important aspect in patients' self-perception regarding activities of daily living, quality of life, and pain.Although the "ability to walk" is one of the items assessed in both MDPS and HHS, the expected benefit of early permissive weight-bearing was not assessed in high-quality, prospective, randomized controlled trials, and its effect size was not calculated for comparison with restricted weight-bearing regimens either.Therefore, the effectiveness of a faster postoperative protocol involving permissive weight-bearing, in addition to measures traditionally described in terms of analgesia, recovery of articular mobility, and muscle strengthening, should be tested, and the outcomes should be assessed and compared to the quality of reduction, complications, and quality of life.Other authors have proposed the same when finding no difference in functional outcome scores or complication rates between early and late weight-bearing protocols for surgically treated acetabular fractures [44,54].Currently, several authors have studied the applicability of innovative gait rehabilitation protocols for temporary or permanent gait impairments, since poor balance control during one's gait and postural maintenance have been associated with disabilities, falls, and increased mortality [55][56][57].These concepts can be extended in the future to rehabilitate patients after surgical treatment of acetabular fractures.
We acknowledge that our study has several limitations, such as the great heterogeneity between the included studies, especially regarding rehabilitation protocols and the direct lack of correlation between these, the quality of reduction, and complications.Moreover, we included studies with patients with associated skeletal or non-skeletal injuries, which can be seen as a major bias as this can affect the choice and timing of rehabilitation protocols.However, our study aimed to systematically review the available literature on rehabilitation practices, including weight-bearing protocols, over time in surgically treated acetabular fracture patients and correlate these practices with functional outcomes.In this context, as previously stated, our findings corroborated other authors who analyzed permissive weight-bearing regimes for patients operated on for articular injuries of the lower limbs.Nevertheless, it is important to mention that all studies included in the final analysis were individual cohort studies or case-control studies with moderate-to-limited levels of evidence.This reinforces the need for urgent, robust, evidenced-based, randomized clinical trials to evaluate the benefits, risks, and indications of permissive weight-bearing after fixation of acetabular fractures.Finally, the use of the current existing patient-reported outcome measurements (PROMs) appears to be insufficient to truly assess the role of the "ability to walk" in terms of pain management, return to a pre-injury functional level, and quality of life, all of which are important components for better understanding the relationship between patient satisfaction and patient trust in the attending physician and the treatment carried out [58][59][60][61].

Conclusions
Our findings suggest that an accelerated postoperative rehabilitation protocol, including early permissive weight-bearing, does not appear to increase the risk of loss of reduction or the rate of complications after surgical treatment of acetabular fractures.However, a proper meta-analysis was not possible, and the heterogeneity of the included studies did not allow us to conclude anything about the potential biomechanical and clinical benefits nor the negative effects related to this rehabilitation regimen in terms of functional results.It is obvious that there is an inconsistent use of PROMs that allows objectively calculating the effect size of the accelerated protocol compared to restricted weight-bearing regimes.In this scenario, we pose the need for higher-level evidence to prove our hypothesis.

Figure 2 .
Figure 2. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram displaying number of studies retrieved following searches and removal criterion at each screening stage.

Figure 2 .
Figure 2. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram displaying number of studies retrieved following searches and removal criterion at each screening stage.

Figure 3 .
Figure 3. Results of the Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I) tool for non-randomized studies, visualized in traffic light plots for each individual domain assessed using Cochrane robvis visualization tool [17-38].

Figure 3 .
Figure 3. Results of the Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I) tool for non-randomized studies, visualized in traffic light plots for each individual domain assessed using Cochrane robvis visualization tool [17-38].

Table 1 .
Characteristics of the 22 included studies.

Table 3 .
Perioperative parameters and form of treatment.

Table 4 .
Quality of reduction, postoperative rehabilitation protocol, and outcome measurement.

Table 5 .
Follow-up period and complications.