Efficacy of Bed Exercise Following Primary Total Hip Replacement in Young Active Patients

Introduction

Total hip replacement (THR) is one of the most effective and consistently successful elective surgeries in orthopedics [1,2], with the number of operations performed increasing dramatically during the past few decades [3,4]. Studies predict a dramatic increase in THR procedures, particularly among patients under 65 years of age, driven by factors such as obesity and osteonecrosis of the femoral head due to steroid use [5,6]. While THR effectively restores hip function, the postoperative rehabilitation process plays a critical role in optimizing outcomes and minimizing complications [7–10].

Rehabilitation following THR generally consists of gait re-education and various exercise regimens. Existing rehabilitation strategies include resistance training, aquatic therapy, and accelerated rehabilitation protocols [11–13]. However, the discussion on existing rehabilitation methods lacks sufficient depth, and more emphasis needs to be placed on their effectiveness in younger patients. While gait re-education has been extensively studied, bed exercises have not been thoroughly evaluated, particularly in terms of their long-term impact on joint function, psychological well-being, and postoperative complications [14].

A more detailed literature review is necessary to support the effectiveness of bed exercises in post-THR rehabilitation. Previous studies have shown that early mobilization, including bed exercises, can prevent complications such as deep vein thrombosis and muscle atrophy. However, long-term outcomes remain unclear, requiring further investigation [15–17].

A detailed literature review revealed that previous studies on bed exercises have had limited follow-up durations and inconclusive results [14,18–20]. Furthermore, prior research has not sufficiently addressed the potential benefits of bed exercises in reducing postoperative complications such as deep vein thrombosis (DVT) and joint stiffness [21,22]. This study fills existing research gaps by providing a longer follow-up period and comparing functional and psychological outcomes between rehabilitation methods. The findings need to be contextualized within broader rehabilitation protocols to provide evidence-based recommendations for improving recovery outcomes in younger THR patients.

Material and Methods

STUDY DESIGN:

This retrospective study was conducted at the Department of Osteonecrosis and Hip Surgery of the Third Hospital of Hebei Medical University. We included patients who underwent unilateral primary THR and divided them into 2 groups based on postoperative rehabilitation treatment: Group A (patients with combined bed exercise and gait re-education) and Group B (patients with gait re-education only). The effectiveness of bed exercise was evaluated comprehensively using the parameters pain, function, range of motion (ROM) of the affected hip, SF-36, and postoperative complications.

Starting on the first day after surgery, patients were encouraged to begin gentle muscle activation exercises. By the third day, ROM exercises were introduced to gradually restore flexibility and joint mobility. As recovery progressed, weight-bearing activities commenced on the fifth postoperative day, allowing patients to transition toward greater functional independence while maintaining a structured and gradual rehabilitation approach.

STUDY POPULATION:

The study retrospectively analyzed the clinical data of patients with end-stage femoral head necrosis or hip osteoarthritis, who underwent primary THR at this department from January 2018 to July 2022. Patients were classified into Group A and Group B based on strict inclusion criteria, ensuring that baseline characteristics were similar. Inclusion and exclusion criteria of involved patients were as follow.

EXCLUDED CRITERIA:

To eliminate the influence of irrelevant factors, all patients underwent THR surgery performed by the same surgical team (a senior surgeon and 2 assistants) through a posterolateral approach (PLA) and received an uncemented prosthesis. The study was approved by the Institutional Review Board of the Third Hospital of Hebei Medical University and was conducted in accordance with the Declaration of Helsinki (ethics approval number K2018-003-1). As it was a retrospective study and all patient information had been de-identified before analysis, this exemption from requiring informed consent was granted by the Ethics Committee of the Third Hospital of Hebei Medical University.

GAIT RE-EDUCATION:

After surgery, patients were encouraged to sit at the edge of the bed and stand with the affected knee straightened. Using a walker, patients were instructed to stand upright, keeping the head, neck, hips, knees, and ankles aligned. They then moved the walker forward slowly to assist walking. The heel landed first, followed by shifting weight to the entire foot, with the rear foot moving as the front foot landed. They were instructed to keep the knee straight and extend the hip as much as possible.

Gait re-education was performed every 2 hours, with the rehabilitation physician gradually increasing walking distance and terrain (from flat corridors to steps/stairs) based on patient progress. Exercise intensity was adjusted based on the patient’s condition, with exercises paused if swelling or pain increased or if the patient was too weak. Both groups adhered to the program for 35 weeks.

BED EXERCISE:

Bed exercises included active hip flexion, active ankle dorsiflexion, and plantar flexion, as well as static quadriceps and static gluteal exercises, performed bilaterally in supine position. These exercises aimed to enhance hip and leg muscle strength and to improve the flexibility of the hip, knee, and ankle joints. Patients were instructed to perform each exercise with 10 repetitions, 5 times daily, starting from the first day after surgery.

Supervision of these exercises was provided daily by qualified rehabilitation physicians with expertise in postoperative rehabilitation. These physicians ensured that patients adhered to the prescribed regimen, monitored the quality of performance, and adjusted the exercises based on individual progress. Compliance with the exercise program was recorded in patient rehabilitation logs, and physicians reviewed these logs during follow-up visits to assess adherence. If a patient had difficulty or was non-compliant, further adjustments were made to the exercise plan.

Patients in Group A were instructed to adhere to this bed exercise program for 35 weeks, in addition to gait re-education.

OUTCOME:

The primary outcome measures were the Harris Hip Score and the Short Form-36 Health Survey (SF-36), both of which are well-established and reliable assessment tools for evaluating patients who undergo total hip replacement (THR) [23,24]. The Harris Hip Score evaluates hip function through 3 components: pain (44 points), function (51 points), and range of motion (ROM) (5 points) [23]. However, because the ROM component is weighted less in the Harris Hip Score, the physical subscale of SF-36 was also used to more clearly capture changes in joint activity. SF-36 is a comprehensive tool for assessing health-related quality of life, consisting of 8 scales that measure physiological function, role-physical, bodily pain, vitality, social function, role-emotional, mental health, and general health. These scales are summarized into 2 general components: the Physical Component Summary (PCS) and Mental Component Summary (MCS), each scored from 0 to 100 [24,25].

Secondary outcome measures included postoperative complications such as lower-extremity deep vein thrombosis, periprosthetic joint infection, prosthetic dislocation, prosthetic loosening, and joint stiffness. These complications were tracked throughout the 35-week period following surgery, with color Doppler flow imaging (CDFI) used to detect deep vein thrombosis in the lower limbs.

Based on our previous research experience, results were recorded preoperatively and at 5, 17, and 35 weeks postoperatively. All data were collected from patient medical records by the same orthopedic surgeon [20].

STATISTICAL ANALYSIS:

Statistical analyses were conducted using SPSS version 26.0 (SPSS, Inc., Chicago, IL) and Excel 2022 (Microsoft Corporation, Seattle, WA). Continuous variables are expressed as mean±standard deviation, while categorical variables are presented as frequencies. The Mann-Whitney U test was used to compare the Harris Hip Score and SF-36 between the 2 groups, as these variables were not normally distributed based on the Shapiro-Wilk test for normality. The comparison of complications between the 2 groups was carried out using the chi-square test and Fisher’s exact test. The relative risk (RR) for complications between the 2 groups was also calculated to assess the relative risk of adverse outcomes. Differences between groups were considered significant when P values were less than 0.05.

To ensure the robustness of the findings, sensitivity analyses were performed using multiple imputation techniques. Missing values were replaced through predictive modeling, and the results were compared with the complete-case analysis. This approach confirmed that the presence of missing data did not significantly alter the study’s conclusions, thus strengthening the reliability of the findings.

Results

GENERAL INFORMATION:

A total of 389 patients who underwent total hip replacement (THR) surgery were included in this study, comprising 224 males and 165 females. The average age was 46.64±13.05 years and the average body mass index (BMI) was 24.29±3.67 kg/m2. Demographic characteristics such as age and BMI have been linked to rehabilitation outcomes in previous studies, with younger patients and those with a lower BMI typically showing better recovery following THR surgery. The nutritional risk screening score (NRS-2002), alcohol consumption, smoking status, whole-body bone mineral density (BMD), and American Society of Anesthesiologists (ASA) classification are presented in Table 1. These factors can influence postoperative recovery and were considered when assessing rehabilitation success.

In terms of the indication for THR surgery, 297 patients had osteonecrosis of the femoral head (ONFH), 61 patients had osteoarthritis of the hip (OA), and 31 patients had developmental dysplasia of the hip (DDH). These conditions are known to affect hip function and rehabilitation outcomes, with patients undergoing surgery for ONFH generally exhibiting more severe preoperative limitations. Patients were divided into 2 groups based on the postoperative rehabilitation methods employed: Group A (combined bed exercise and gait re-education) and Group B (gait re-education alone). The rationale for this division was to assess the added benefit of bed exercise in the rehabilitation process. Group A received a comprehensive rehabilitation program, including bed exercises aimed at enhancing muscle strength and flexibility, in addition to gait re-education, while Group B only received gait re-education. The expected outcome for Group A was enhanced functional recovery, pain reduction, and a more rapid return to daily activities, while Group B was expected to primarily benefit from improved gait and mobility.

A comparison of baseline characteristics between the 2 groups is shown in Table 1, and there were no statistically significant differences observed. This suggests that the 2 groups were similar in terms of demographic and clinical factors before undergoing the assigned rehabilitation methods, allowing for a fair comparison of outcomes between the groups.

EFFICACY OF BED EXERCISE IN HARRIS HIP SCORE AFTER TOTAL HIP REPLACEMENT:

To evaluate the impact of bed exercise on rehabilitation outcomes following total hip replacement (THR), Harris Hip Scores were compared between patients who underwent bed exercise (Group A) and those who did not (Group B). The preoperative Harris Hip Scores were used as the baseline, and no significant difference was observed between the 2 groups prior to surgery (P>0.05).

However, at 5 weeks postoperatively, Group A had a significantly higher Harris Hip Score (78.1±9.4) compared to Group B (71.5±12.9) (P=0.036), indicating that the combined rehabilitation method (bed exercise and gait re-education) resulted in better early postoperative outcomes. By 17 weeks postoperatively, the differences between the 2 groups were diminished (Group A: 87.3±7.8 vs Group B: 83.2±8.5, P=0.294), and at 35 weeks postoperatively, no significant difference was found (Group A: 95.0±6.2 vs Group B: 92.8±6.9, P=0.558). It is important to note, however, that Group A consistently had higher Harris Hip Scores at all postoperative time points.

To better assess the effects of bed exercise on rehabilitation, the individual sub-scores for pain (0–44) and function (0–51) were analyzed (Table 2). The baseline values for these parameters showed no significant differences between the 2 groups (P>0.05). At 5 weeks postoperatively, Group A had significantly greater improvements in pain relief (P=0.032) and functional recovery (P=0.027) compared to Group B. Moreover, at all follow-up points, patients in Group A had superior recovery in terms of hip pain, daily activities, walking speed, and walking distance.

Similar trends were observed in the range of motion (ROM). Notably, at 5 weeks postoperatively, the abduction angle in Group A was significantly higher than in Group B (44.9±13.4 vs 37.2±12.9, P=0.029). This difference persisted at 17 weeks postoperatively (Group A: 51.5±9.4 vs Group B: 43.3±8.2, P=0.041), but by 35 weeks postoperatively, no significant difference in abduction was observed between the 2 groups (P=0.459).

While these findings suggest the benefit of combining bed exercise with gait re-education, it is important to note potential confounding factors that could influence outcomes, such as the patients’ baseline characteristics, including age, BMI, and comorbid conditions. These factors may have affected recovery trajectories, and future studies could benefit from adjusting for these variables to further clarify the effectiveness of bed exercise in improving rehabilitation outcomes.

EFFICACY OF BED EXERCISE IN SF-36 AFTER TOTAL HIP REPLACEMENT:

The SF-36 was simplified into a physical component summary (PCS) scale (0–100) and a mental component summary (MCS) scale (0–100) to provide a clear evaluation of bed exercise’s effectiveness in improving postoperative quality of life. Before THR surgery, there was no significant difference between PCS of patients in different groups (45.4±21.9 vs 43.7±24.1, P=0.792). At 5 weeks postoperatively, both groups showed significant improvements in PCS, with Group A demonstrating significantly higher scores than Group B (82.6±14.1 vs 73.1±16.0, P=0.019). Nevertheless, comparison of PSC between the 2 groups showed no statistically significant difference at 17 or 35 weeks after surgery. In terms of MCS, there was no statistically significant difference in baseline results of the 2 groups (P=0.812). However, the MCS scores of Group A had increased more at 5 weeks after surgery than in Group B (80.5±16.9 vs 67.9±18.8, P<0.001), and this difference persisted at 17 weeks after surgery (89.1±12.7 vs 79.9±13.6, P=0.037). The details are provided in Table 3. This pattern indicates that while physical recovery (as measured by PCS) tends to converge between the 2 groups over time, the mental and emotional recovery (as measured by MCS) continues to benefit from the combined rehabilitation approach, even in the long term. These findings highlight the potential long-term psychological benefits of incorporating bed exercises into the rehabilitation program following THR.

EFFICACY OF BED EXERCISE IN POSTOPERATIVE COMPLICATIONS AFTER TOTAL HIP REPLACEMENT:

To assess the role of bed exercise in reducing postoperative complications, the incidence of postoperative complications was comprehensively tracked, including deep vein thrombosis (DVT), joint stiffness, periprosthetic joint infection, prosthetic dislocation, and prosthetic loosening. Table 4 has been revised to ensure accurate representation of these complications across both groups. Notably, deep vein thrombosis (DVT) occurred significantly less frequently in Group A, with only 5 patients (2.7%) developing lower-limb venous thrombosis, compared to 29 patients (14.1%) in Group B (P<0.001). In Group B, DVT cases involved multiple blood vessels or intermuscular veins, with symptoms including leg swelling and pain in some patients, while others were asymptomatic. In contrast, Group A had fewer cases of DVT, with only intermuscular vein thrombosis detected, and symptoms were generally milder. No cases of pulmonary embolism were observed in either group. These findings suggest that combined bed exercise and gait re-education can reduce the incidence of DVT postoperatively. Joint stiffness was another complication significantly reduced in Group A, with 1.1% of patients experiencing stiffness compared to 5.3% in Group B (P=0.020). Stiffness was primarily associated with limited hip movement and mild limping in the early postoperative period, but all symptoms resolved by 17 weeks after surgery.

For the remaining complications-periprosthetic joint infection, prosthetic dislocation, and prosthetic loosening-the incidence was lower in Group A than in Group B, but the differences were not statistically significant (Table 5). Relative risk (RR) analysis revealed that bed exercise significantly reduced the risk of DVT (RR=0.194, 95% CI: 0.077–0.491), supporting its potential as a preventive measure for DVT. Additionally, the risk of joint stiffness was reduced in Group A (RR=0.205, 95% CI: 0.046–0.911, P=0.020). However, bed exercise did not show a significant effect on reducing the risk of periprosthetic joint infection, prosthetic dislocation, or prosthetic loosening.

Discussion

Currently, patients are suggested to perform rehabilitation exercises combining gait re-education and bed exercises after surgery in clinical practice [26,27]. Although this combined regimen appears to be effective in helping patients improve lower-limb function and resume normal activities, it is unclear whether bed exercise is a necessary component of this postoperative rehabilitation regimen. Moreover, there are few studies on the effectiveness of bed exercise during this phase, especially focusing on its effect for young patients. In this study, bed exercise showed obvious rehabilitation efficacy for young patients with THR. Our study found that: (1) Bed exercise could improve the pain, function and ROM of hip joint in young patients with THR at an early postoperative stage; (2) Bed exercise has a considerable beneficial effect on improvement of postoperative quality of life, especially in mental aspects; (3) Bed exercise contributes to reducing the incidence of deep vein thrombosis and joint stiffness. These findings underscore the importance of integrating structured bed exercises into standard rehabilitation protocols for younger THR patients. The early postoperative advantage seen in pain relief, functional recovery, and complication reduction highlights its effectiveness in expediting rehabilitation. Clinicians and physical therapists should consider implementing structured bed exercise regimens as a core component of post-THR recovery, particularly for patients aiming for faster reintegration into daily activities and work.

There have been few studies on the postoperative rehabilitation effectiveness of bed exercise for young patients with THR. In our analysis, bed exercise was found to be beneficial to relieve hip pain and improve hip function and ROM, but it did not influence the postoperative hip rehabilitation in previous research [21,27]. Jesudson and Stiller suggested that although measured outcomes were generally improved over the study period after THR, they found no significant difference between patients receiving bed exercise and those who did not for any outcome measured at any time point. However, their follow-up duration was limited to inpatient recovery, typically lasting less than 2 weeks. In contrast, our study extended follow-up to 35 weeks, demonstrating that early functional gains translate into sustained psychological benefits and reduced complication rates over time. Similar to the previous study, pain score, function score, and range of motion on 6 directions had different degrees of improvement after surgery, but there were obvious differences in degree of improvement for outcome parameters between our 2 groups at 5 weeks after surgery [22]. This difference may be related to the follow-up time. In Jesudson’s study, they justified only analyzing measurement outcomes when patients remained in the hospital. They only chose postoperative days 3–4 and postoperative days 7–8 as the timing of the outcome measurements. It should be noted, however, that, in our study, the follow-up time was extended to 35 weeks after surgery, which may result in different results compared with the previous study. In addition, the included patients were younger people under age 65 years, which may be another reason for the different results between our study and Jesudson’s study. The difference for most outcome parameters between patients with or without bed exercise had disappeared by 17 weeks after surgery, except for range of abduction motion. At 17 weeks after surgery, abduction ROM of patients in Group A was 51.5±9.4 while that of patients in Group B was 43.3±8.2 (P=0.041). It has been confirmed that the reduced myodynamia of hip abductor can increase the incidence of prosthetic dislocation after total hip replacement [28]. Du Zhiye et al found that inadequate functional abductor musculature contributed to risk of hip dislocation [29]. Song et al evaluated the dislocation rate after total hip replacement with constrained acetabular liners, reported that patients with a lower abductor muscle weakness grade had a high incidence of dislocation [30]. This conclusion demonstrates that abductor weakness is a risk factor for prosthetic dislocation after total hip replacement. At 5–17 weeks after surgery, there was a difference in abduction ROM of patients between our 2 groups, but it did not affect the dislocation rate. Four patients in Group A and 7 patients in Group B had prosthetic dislocation, and there was no significant difference between the 2 groups (P=0.472). The difference in abduction ROM had disappeared by 35 weeks after surgery, which indicates that bed exercise can influence early functional rehabilitation of the abductor muscle, increase muscle strength, and improve muscle activity.

It was previously established that clinicians and patients disagree in evaluation of surgery and rehabilitation effectiveness, so it is necessary to evaluate rehabilitation effects from the patient’s perspective. Currently, many self-assessment scales have been shown to be useful for assessing quality of life after total hip replacement. Soohoo et al compared use of SF-36 and WOMAC in patients undergoing THR, reporting that SF-36 was reliable and sensitive to changes in outcomes after THR [31]. Thus, SF-36 was chosen as one of the major outcomes to assess the quality of patient’s postoperative life. We found that at 5 weeks after surgery, there was a significant difference in SF-36 between the 2 groups, which seems to be consistent with the difference in Harris score. This shows that the feeling of pain and limitation of hip movement and function can affect both physical and mental domains. Tarakji’s study focused on improvement in depressive symptoms after THR and suggested that THR significantly improved hip function and pain in depressed patients, thereby improved their depressive symptoms [32]. In addition, it should be noted that the difference in MCS still existed at 17 weeks after surgery. The recovery time following surgery was slightly longer for patients who did not receive bed exercise. At 17 weeks after surgery, although there was no significant difference in outcomes as diverse as pain score and function score, patients in Group B tended to be dissatisfied with the rehabilitation effect, which affected SF-36 scores. This suggests that although physical function scores eventually converged in the 2 groups, psychological recovery in patients performing bed exercises was sustained longer. Several potential confounding factors may explain this trend, including differences in preoperative mental health status, social support, employment demands, and expectations for recovery. Future studies should control these variables to provide a clearer understanding of the mechanisms driving prolonged psychological benefits. In addition, from a social perspective, many patients need to return to work as soon as possible, which may be another reason for the lower MCS scores in Group B.

Regarding complications, we found a difference in the incidence of joint stiffness between the 2 groups—2 patients in Group A (1.1%) and 11 patients in Group B reported having stiffness at follow-up. Stiffness was reported as one of the most common minor complications after THR. In a study of complications to 6 months following total hip arthroplasty, Heo et al found that stiffness was one of the most frequently reported minor complications, with an incidence of 8.8% [33]. Joint stiffness mostly occurred within 5 weeks after surgery. Similarly, pain, functionality, and ROM of patients in Group A was better than in Group B at 5 weeks after surgery, which indicated that the effect of bed exercise on reducing the incidence of joint stiffness may be related to the effects of bed exercise in relieving pain and recovery of hip function. In addition, stiffness is a legitimate patient experience that can affect the postoperative SF-36 score. In psychological research, Balck et al showed that illness perception can influence functionality, pain, stiffness, and activity of daily living after total hip replacement [34]. At 5–17 weeks after surgery, SF-36 scores in Group A were generally higher than in Group B, which may be why fewer patients in Group A had joint stiffness. Another difference exists in the incidence of deep vein thrombosis between patients in Group A and Group B. Surgery and limited lower-extremity activity are major factors affecting the formation of deep venous thrombosis, which is one of the most common and dangerous complications after THR. To prevent deep vein thrombosis, patients underwent subcutaneous injection of low-molecular-weight heparin (LMWH) for 5~7 days before discharge and were prescribed rivarsaban for 1 month after discharge. In this study, we found DVT rates of 2.7% and 14.1% for Group A and Group B, respectively (P<0.001). This significant difference was correlated with ankle motion in Group A. Imai et al found that manual calf massage and ankle motion could reduce the incidence of DVT after THR [35]. Venous blood flow and venous blood flow velocity are increased by compression of the calf vein when patient performed ankle exercise, which could decrease long-term blood stasis. It has also been reported that ankle motion can produce high flow pulsatility and activate clotting factors in the soleal veins, which aids in DVT prevention [36].

There are some limitations in the current study. First, it was retrospective, so there may be some retrospective bias. Second, we only included younger patients with unilateral hip joint disease who underwent primary THR, which may limit the universality of the results. Third, the rehabilitation exercise intensity for bed exercise depends on the response of patients, and the exact effect of bedside exercise intensity and duration remains uncertain. Potential confounding factors such as baseline psychological health, socioeconomic status, and preoperative physical activity levels were not controlled. The observed persistence of MCS differences may be influenced by these variables, highlighting the need for future randomized controlled trials with larger sample sizes to validate these findings. Fourth, all included patients underwent THR performed with a posterolateral approach, but some studies suggested that because different surgical approaches involve different muscle groups, surgical approach should be considered as a potential variable. Compared to patients undergoing the posterolateral approach, those with the anterolateral approach had poorer recovery of abduction function. Li et al found that 2 patients had claudication (physical examination: abduction dysfunction of hip) after THR through the anterolateral approach [37]. Therefore, further study is needed to assess whether the outcomes following bed exercises, especially ROM and complications, are influenced by surgical approach.

Conclusions

This study demonstrated that incorporating bed exercises into postoperative rehabilitation significantly enhances hip function, improves overall quality of life, and reduces the incidence of complications such as deep vein thrombosis and joint stiffness in younger patients undergoing THR. These findings highlight the crucial role of structured bed exercises in optimizing early functional recovery and long-term psychological well-being. Given its simplicity, cost-effectiveness, and ease of implementation, bed exercise should be actively integrated into standard rehabilitation protocols for younger THR patients.