No need for hip precautions after total hip arthroplasty with posterior approach: A systematic review and meta-analysis

Abstract

Background:

Nowadays, total hip arthroplasty (THA) is one of the most successful procedures in the field of orthopedics and trauma. The posterior approach has historically been associated with a higher rate of hip dislocation. To reduce the rate of hip dislocation in the posterior approach, most orthopedic surgeons would recommend hip precautions (HP) for their patients postoperatively based on previous theories. However, recent randomized controlled trials have shown no significant difference in hip dislocation rates with or without HP, in contrast to previous theories. Based on these, this study conducted a meta-analysis of these randomized controlled trials to try to get qualitative conclusions.

Methods:

Randomized controlled trials of HP after THA up to July 28, 2023, were searched in 3 databases, PubMed, Embase, and the Cochrane Library. Data extraction and literature quality assessment were performed by 2 independent authors and extracted hip dislocation, hip disability and Osteoarthritis Outcome Score, joint replacement (HOOS JR) scores over 6 weeks, and time to discontinuation of mobility aids. Stata software and Revman software were used to perform this meta-analysis.

Results:

Following screening, 3 papers with a total of 1215 participants were included in the analysis. This meta-analysis showed that there was no statistically significant difference in hip dislocation rates with or without HP after THA undergoing the posterior approach and that the without HP group instead showed better outcomes in terms of HOOS JR scores and time to discontinuation of mobility aids.

Conclusion:

THA with a posterior approach does not require hip precautions.

1. Introduction

Nowadays, total hip arthroplasty (THA) is one of the most successful procedures in the field of orthopedics and trauma.^[1] THA is increasingly being used to treat hip disease because of its ability to significantly improve pain, function, and quality of life for patients with hip disease.^[2,3] More than 1 million hip replacements are performed worldwide each year. Although there are a variety of surgical approaches to total hip arthroplasty, each with its advantages and limitations,^[4–6] the posterior approach remains one of the most common and widely used surgical approaches. The posterior approach, as one of the most popular surgical exposures, has the advantage of a short operative time and a low incidence of postoperative claudication and abduction dysfunction. Although there are different types of posterior approaches such as Moore, Gibson, and posterolateral, all use the gluteus maximus split without damaging the gluteus medius and minimus muscles.^[7] Exposure of the hip in the posterior approach requires incision of the posterior joint capsule and external rotator group, and thus the posterior approach seems to have been historically associated with a higher rate of hip dislocation.^[4] Dislocation is the number 1 cause of revision after THA before aseptic loosening and infection of the acetabular or femoral component.^[8] The incidence of dislocation after the primary THA ranged between 0.12% and 16.13%.^[9] Between 11% and 24% of revision THAs are used to treat hip dislocations.^[10] The rate of dislocation after revision THA was also high: between 6.6% and 21.2%.^[11–13] Based on prior theory, most orthopedic surgeons advise postoperative hip precautions (HP) to avoid specific movements and activities that may endanger the hip’s stability to lower the hip dislocation rate in the posterior approach. These actions often involve hip inversion over the midline, flexion above 90 degrees, and internal and external rotation above 20 degrees from the neutral position.^[14] Although HP after THA are currently widely used in clinical practice,^[1] they are not supported by clinical research evidence yet. Furthermore, HP may influence the effects of enhanced rehabilitation after surgery to some extent, and increase the risk of falls during the recovery period. At the same time, excessive focus on these restrictions has the potential to increase patients’ psychological anxiety and distress. Based on these, several researchers have recently designed randomized controlled trials to investigate whether postoperative hip precautions are necessary. In contrast to previous theories, the results of these studies indicate that there is no significant difference in hip dislocation in the posterior approach to THA with or without HP. To date, there are no meta-analyses to summarize the results of these randomized controlled trials. The purpose of this study was to meta-analyze these studies to try to find out if a qualitative conclusion could be drawn.

2. Materials and Methods

2.1. Study protocol and registration

Since all of the data used in this study was taken from previously published sources or databases, there was no need for an ethical review or patient publication consent. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement^[15] was followed when conducting this systematic review and meta-analysis. The a priori protocol for this meta-analysis is available in the International Prospective Register of Systematic Reviews: CRD42022349268.

2.2. Search strategy

Randomized controlled trials of HP after THA up to July 28, 2023, were searched in 3 databases, PubMed, Embase, and the Cochrane Library. The search strategy used in PubMed is as follows:(((((((Arthroplasty, Replacement, Hip[MeSH]) OR (Total Hip Replacement[Title/Abstract])) OR (Total Hip Arthroplasty[Title/Abstract])) OR (Hip Prosthesis Implantation[Title/Abstract])) OR (Total Hip Arthroplasties[Title/Abstract])) AND ((((postoperative precautions[Title/Abstract]) OR (Hip Prophylaxis[Title/Abstract])) OR (Postoperative restrictions[Title/Abstract])) OR (hip precautions[Title/Abstract]))) AND (((((posterior[Title/Abstract]) OR (Posterior access[Title/Abstract])) OR (Posterior approach[Title/Abstract])) OR (posterolateral access[Title/Abstract])) OR (posterolateral approach[Title/Abstract]))) AND (((random allocation[Mesh]) OR (clinical trial[Publication Type])) OR (clinical trial[Title/Abstract])).

2.3. Study selection

The inclusion criteria: all included studies were the results of randomized controlled trials; patients over 18 years old who underwent an initial THA with the posterior approach accompanied by repair of the posterior capsule and external rotator muscles; outcome included hip dislocation events with a follow-up time of 6 weeks or more.

The exclusion criteria: studies in non-English languages; non-randomized controlled study; participants were younger than 18 years of age; non-elective hip replacement (e.g., femoral neck fracture); non-primary THA (e.g., revision THA); hemiarthroplasty; cognitive impairment, neuromuscular dysfunction, and/or substance abuse that prevented understanding and compliance with study procedures.

Two additional independent authors identified the included studies using the predetermined inclusion and exclusion criteria, while 1 author carried out the search in accordance with the predetermined search strategy. These 2 authors discussed and conferred to resolve the screening process, with the final opinion, if necessary, being determined by a third author. During the process of screening the literature, the names of the journals and authors were not concealed.

2.4. Data extraction and quality assessment

Two authors independently extracted data from the original literature and evaluated the quality of the literature. When there are differences of opinion between the 2 independent authors, attempts are made to resolve such differences through discussion and negotiation, with decision-making delegated to a third author when necessary. The primary outcome of the study was the probability of hip dislocation, as the primary aim of this study was to judge whether the presence or absence of HP after THA had an impact on the occurrence of hip dislocation. Secondary outcomes included Hip disability and Osteoarthritis Outcome Score, joint replacement (HOOS JR) scores over 6 weeks, and time to discontinuation of mobility aids. The HOOS JR score is a brief patient-reported outcome measure developed in 2016 to assess pain and function before and after THA, which was derived from the original HOOS score containing 40 questions to a brief survey containing only 6 questions.^[16] It included 6 items with appropriate and acceptable attributes of individual ability and item difficulty and correctly ordered responses for each item in the individual’s functional hip ability. The HOOS JR score was adjusted to a total score of 100 as was the original HOOS score scale, with 0 representing hip total disability and a score of 100 representing perfect hip health. In addition, for some of the literature that only reports the study results through figures, GetData Graph Digitizer 2.26 software was used to extract the data from it. The Cochrane Risk of Bias Assessment tool 2.0 (Rob2.0)^[17] was used to evaluate the quality of the literature. The reviewers’ answers to the signal questions were used to classify the risk of bias for each domain into 3 levels: “low risk,” “some concerns,” and “high risk.” When there was disagreement, the 2 authors discussed it and, if necessary, sought advice from a third author before coming to a decision. Each author evaluated the literature independently.

2.5. Statistical analysis

Both continuous (HOOS JR scores and time to discontinuation of mobility aids) and dichotomous (number of cases of hip dislocation) outcomes were present in the data we extracted from the original study. For hip dislocation, the sample size and the number of cases of hip dislocation occurring in the test and control groups were extracted, and compared using the Mantel–Haenszel method to calculate the odds ratio (OR) including 95% confidence interval (CI). For the HOOS JR score, the mean difference (MD), standard deviation, and sample size of the difference between the 2 groups before and after treatment were extracted. For the time of stopping the use of mobility aids and canes, the MD, standard deviation, and sample size of the time of stopping the use of mobility devices in both groups were extracted. Both of them were analyzed using the Inverse Variance method to calculate the MD, including 95% CI. The decision of which statistical model (fixed effects model, random effects model) to use to analyze the data for the included studies depended on the significant heterogeneity between studies. The I² statistic was used to assess heterogeneity. I² represents the magnitude of heterogeneity, while I² ≤ 50% is defined as acceptable in the Cochrane Handbook. If I² ≤ 50%, a fixed-effects model was chosen; otherwise, a random-effects model was used. If there was significant heterogeneity between the results, we performed sensitivity analyses to find the source of heterogeneity by subgroup analysis. P < .05 was considered statistically significant. Meta-analysis was performed using RevMan 5.4 software, and all data analyses are presented as forest plots. Additionally, we conducted an Egger test with Stata 17 software to check for publication bias, and P < .05 was regarded as a significant level of publication bias.

3. Results

3.1. Research selection and characteristics of included study

By literature search, a total of 54 relevant papers or trials in these 3 databases were searched, including 15 in Pubmed, 3 in Embase, and 36 in the Cochrane Library for randomized controlled trials databases. 35 studies were left after 19 duplicates were removed. By scanning the titles of the remaining literature or trials, 31 studies were eliminated: 7 on surgical technique comparisons, 5 on revision hip replacement surgery, 4 on postoperative complications, 2 on research protocols or studies with unpublished results, 2 on total knee arthroplasty studies, 2 on prosthetic materials, 2 on anesthesia techniques in THA, and 6 for additional exclusion criteria. One of the remaining 4 studies, a comparative investigation of hip sleep restriction and non-restriction, was ultimately disregarded. Ultimately, 3 studies in all were used for the analysis.^[18–20] The entire literature screening process is displayed in Figure 1. All included studies were published in the last 3 years (2019–2022), were conducted in the United States, none reported patient race or ethnicity, and had a total sample size of 1215, including 605 in the no hip precautions (NHP) group and 610 in the HP group. There were no statistical differences in preoperative demographic baseline characteristics between the 2 groups within all studies. Characteristics of the data extracted from the studies are displayed in Table 1. The included studies all used a posterolateral approach and all performed repair of the posterior joint capsule and short external rotator muscles. The abduction angle and anterior inclination of the acetabular cup were reported in the study by Dietz et al. The abduction angle was 42.5° in the HP group vs 42.6° in the NHP group (P = .94), and the anterior inclination angle was 18.8° in the HP group vs 14.9° in the NHP group (P = .02). In the study by Mounts et al, all acetabular cups were reported to be in the range of 40 ± 5° of abduction and 15° to 20° of anterior inclination, and the femoral stalks had an anterior inclination angle of 15°. In the study by Tetreault et al, the acetabular cups were reported to be positioned at approximately 40° of abduction with 15° to 20° of anterior tilt. The femoral stem had an anterior inclination of 10° to 15°. Both the Mounts et al and Tetreault et al studies reported intraoperative stability testing of the hip joint for 90° of flexion, 45° of internal rotation, and 0° of adduction. The HP group of all included studies was instructed by their healthcare providers to avoid hip flexion over 90°, internal rotation, and internal retraction; the NHP group was told that hip precautions were not needed. However, NHP patients in the Tetreault et al study were told to use devices such as elevated toilets to enhance comfort, and the other studies were not.

Figure 1.

Flowchart of the trail selection.

Table 1.

Characteristics of data extracted from the included studies.

Study	Dietz et al (2019)		Mounts et al (2022)		Tetreault et al (2020)
Location	USA		USA		USA
Group	NHP	HP	NHP	HP	NHP	HP
Sample size	139	145	172	174	294	291
Mean age (yr)	63.2 ± 0.71	63.3 ± 0.77	66.9 ± 11.3	66.1 ± 9.90	62.6 ± 9.6	63.9 ± 9.3
BMI	31 ± 0.46	30 ± 0.43	28.9 ± 4.95	29.8 ± 5.47	32.1 ± 8.14	32.9 ± 8.49
Female	51.1%	44%	55.2%	50%	57.7%	51.1%
Follow-up time	2 wk; 6wk 3 mo; 12 mo		2 wk; 6wk 3 mo; 12 mo		2 wk; 6 wk 3 mo; 12 mo
Adherence rate	61% (2 wk) 72% (6 wk)	95% (2 wk) 90% (6 wk)	Unreported	Unreported	77.9%	74.6%
Dislocation	1	2	0	4	2	3

3.2. Assessment of risk of bias

The risk of bias was assessed as shown in Figure 2. All studies were evaluated as low risk in the randomization process, missing outcome data, measurement of the outcome, and selection of the reported result. Deviations from intended intervention items were evaluated as some concerns, and the overall risk of bias was evaluated as some concerns for all studies. Due to the specificity of the interventions, patient-blinded implementation was not possible. Also, there are many ways for patients to learn about hip precautions, including the internet, and patient compliance with the interventions is hardly perfect. Patient adherence was not tested in the study by Mounts et al.^[19] In contrast, the studies by Dietz et al^[18] and Tetreault et al^[20] assessed patient adherence by patient self-report at return interviews. In the study by Dietz et al there was a statistically significant difference between the HP and NHP groups on the “ Hip precautions practiced “, “ No hip flexion > 90°,” “ No internal rotation “, “ No adduction “ were statistically different on all these items (P < .05). In contrast, the study by Tetreault et al simply reported that both possessed similar nonadherence (25.4% and 22.1%).” In summary, although all studies were ultimately evaluated as having some concerns, we still considered these studies to be high-quality randomized controlled trials in the field and included all trials in the analysis.

Figure 2.

Risk of bias graph.

3.3. Statistical analysis

All included studies reported hip dislocation events. The results of the meta-analysis showed no statistically significant difference in hip dislocation rates with or without HP (OR = 0.37, 95% CI = [0.11, 1.26], P = .11, I² = 0%, Fig. 3). Two studies reported HOOS JR scores, and this study analyzed their results at 6 weeks, 3 months, and 12 months postoperatively and placed the analyses in the same forest plot (Fig. 4.). The results showed that all HOOS JR score results beyond 6 weeks suggested better hip health in the group without HP: for the 6-week postoperative follow-up results, MD = 2.80, 95% CI = [2.23, 3.37], P < .01, I² = 0%; for the 3-month postoperative follow-up results, MD = 3.97, 95% CI = [3.41, 4.53], P < .01, I² = 0%; for the 12-month postoperative follow-up, MD = 2.57, 95% CI = [1.80, 3.33], P < .01, I² = 0%. Two studies reported the time to discontinuation of mobility aids. The specific mobility aids used varied among the included studies, so only items that reported the same mobility aids were selected for meta-analysis in this study and the results of the analysis were also summarized in the same forest plot (Fig. 5). For those who used the walker aid, the results of the meta-analysis showed that the NHP group stopped using it earlier (MD = −0.59, 95%CI = [−0.87, −0.31], P < .01, I² = 0%); for those who used the cane aid, the results of the meta-analysis also showed that the NHP was used earlier (MD = −0.58, 95%CI = [−0.95, −0.21], P = .002, I² = 0%), both of which were statistically different. In addition, we performed an Egger test with Stata 17.0, P = .3587 > 0.05, with no significant publication bias.

Figure 3.

Dislocation of the hip joint. NHP = no hip precautions, HP = hip precautions.

Figure 4.

HOOS JR scores. NHP = no hip precautions, HP = hip precautions.

Figure 5.

Discontinuation of mobility aids. NHP = no hip precautions, HP = hip precautions.

4. Discussion

THA is primarily used to treat advanced osteoarthritis. Significant specific risks for osteoarthritis of the hip include age, gender, trauma, and joint morphology. Therefore, as the global population ages, the incidence of osteoarthritis is estimated to increase, leading to a continued increase in the need for primary total hip replacements. The study that Singh et al^[21] conducted predicts that by 2040 there will be 1429,000 total hip replacements performed annually in the U.S. alone. THA dislocations are one of the primary reasons for revision surgery, according to registry data. Approximately 8% to 12% of hip operations performed today are revision surgeries, with 11% to 24% being for postoperative THA dislocations.^[10] A posterior approach to the hip with dissociation of the external rotators and posterior joint capsule has a higher rate of postoperative dislocation than other surgical methods,^[7] according to numerous studies. However, through the anatomic restoration of the external rotators and posterior capsule, as well as greater anteversion of the cupped component, the high dislocation rate induced by this posterior approach can be greatly reduced to 0.7%.^[7,22] The posterior approach, originally described by Von Langenbeck^[23] and later by Gibson^[24] and Moore,^[25] did not emphasize the importance of maintaining soft tissue tone and did not include repair of the external rotators and posterior capsule as part of the surgery. With progress in research, more and more researchers are realizing the importance of repairing the posterior capsule and external rotators to maintain joint stability.^[26] The posterior approach to THA has also evolved into the most widely used posterolateral approach, accompanied by various posterior soft tissue repair techniques. In addition, some studies have found that almost half of dislocations occurred as a result of accidental motion^[27] (e.g., a fall or twist) and that hip precautions were unlikely to help.^[28] This study demonstrated that NHP does not increase hip dislocation rates after anatomic repair of the external rotators and posterior capsule following THA with a posterior approach; on the contrary, NHP has better efficacy metrics in terms of HOOS JR scores and time to discontinuation of mobility aids. This is also consistent with the findings of a recent analysis of the UK national dataset, which found that there was no significant difference in postoperative hip dislocation and readmission rates after initial THA with or without HP, and that even after discontinuation of HP, the dislocation rate appeared to decrease, as well as evidence that discontinuation of HP reduces the length of stay and has the potential for significant cost savings.^[29] Given that the posterior approach was employed in 57.6% of registrations for initial THA surgeries in the UK, the findings of this study are extremely useful for our analysis.^[30] The good results in the NHP group in terms of HOOS JR scores and discontinuation of mobility aids were also similar to the results of previous studies,^[31,32] and the probable reason for this outcome was that the NHP group was able to exercise more freely early on, accelerating the recovery rate.^[32,33] Although most of the previous analyses of randomized controlled trials for the presence or absence of HP on these outcome metrics were not statistically different, both also suggested a trend toward better outcome metrics in the NHP group. There are valid reasons to believe in the results of our meta-analysis, even though they may appear overly aggressive when compared to earlier theories. The absence of hip precaution offers a demonstrable advantage in terms of a speedy postoperative recovery and, at the very least, does not lead to a higher rate of hip dislocation.

In terms of financial costs, patients who received HP had higher financial costs. Peak et al^[31] found additional expenditures of $655 per patient in the restricted group, and these costs were primarily related to the additional equipment and fixtures required, including elevated toilet seats, abduction pillows, and elevated chairs. These were also without accounting for the cost of time required for rehabilitation and lost wages. Although none of the previous randomized controlled trials have examined the economic loss of the NHP and HP groups in terms of the impact on return to work due to differential postoperative recovery times, the trial by Tetreault et al^[20] demonstrated that at the 6-week follow-up, unrestricted patients found it less difficult to perform activities of daily living (i.e., washing and dressing), resumed driving earlier, and slept more on their sides, suggesting to some extent that no hip prophylaxis is beneficial for patients’ rapid postoperative recovery, and therefore the implementation of hip precautions is likely to result in some degree of economic loss and social burden to the individual. On the Sacks et al^[34] study, it was also demonstrated that the UK could possibly save up to $35 million a year in hospital stays, rehabilitation tools, physical therapists, and nursing staff if all hospitals stopped performing hip prevention in 2019. Therefore, the posterior approach to total hip arthroplasty without hip prophylaxis seems to be better because it has similar hip dislocation rates, better postoperative recovery, and lower economic costs.

However, this meta-analysis has some limitations. First, the small number of randomized controlled trials included in this meta-analysis largely limits the credibility of the results of the meta-analysis. Since hip-free restriction is a different concept from the one we have widely agreed on in the past, there are great difficulties in trial implementation, ethical adoption, and patient acceptance, which is the main reason for the lack of relevant randomized controlled trials. A high quality meta-analysis could help to ameliorate this dilemma by providing a high level of evidence-based medical evidence for such interventions, which is what we sought to do in this meta-analysis despite our limited capacity. Second, due to the specificity of the intervention, patient-blinded implementation was almost impossible, and patients in the NHP group also had the opportunity to learn about hip prophylaxis through the Internet and implement it on their own, which could also affect patient compliance with the intervention to some extent and thus affect the results of the randomized controlled trial and this effect could not be eliminated. Third, the THA procedures in the included studies were performed by or under the direct supervision of senior surgeons, and therefore, this also influenced to some extent the general applicability of the results of our analysis. Factors affecting the rate of postoperative hip dislocation after THA surgery do not only lie in postoperative hip prophylaxis alone, but also encompass the stability of the patient’s own hip muscles and capsule, different surgical approaches, the specification and positioning of the acetabular and femoral component prostheses, soft tissue tension, and the experience of different surgeons.^[35–37] Fourth, since neuromuscular disorders affecting the hip muscles and joint capsule can also affect the stability of the hip joint, although the included trials excluded these effects to a greater or lesser extent in the inclusion-exclusion criteria, the rigor with which the inclusion criteria were implemented varied among investigators, especially since there is no clear uniform diagnostic index for sarcopenia, which can also affect the reliability of the results to some extent.

5. Conclusion

In conclusion, this meta-analysis showed that there was no statistically significant difference in hip dislocation rates with or without HP after THA undergoing the posterior approach and that the NHP group instead showed better outcomes in terms of HOOS JR scores and time to discontinuation of mobility aids. As a result, while no hip precautions do not increase the likelihood of hip dislocation following THA, they may be more helpful for patients’ early and rapid recovery and reduce the economic cost to individuals and society.

Author contributions

Conceptualization: Jiale Guo.

Formal analysis: Xianglong Liu.

Methodology: Qionghan He, Xianglong Liu.

Project administration: Yehai Li.

Software: Jiale Guo, Yue Sun.

Validation: Yue Sun, Xianglong Liu.

Writing – original draft: Jiale Guo, Qionghan He.

Writing – review & editing: Yehai Li.