Orthopedics

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Feature Article 

Evaluation of Reducing Postoperative Hip Precautions in Total Hip Replacement: A Randomized Prospective Study

Prodromos A. Ververeli, MD; Eric B. Lebby, MD; Cheryl Tyler, RN; Carol Fouad

Abstract

Currently, many rehabilitation protocols for total hip replacements (THRs) include activity restrictions to prevent postoperative dislocation. There is increasing demand for more efficient and safe rehabilitation protocols. This randomized prospective study evaluates the need for hip restrictions following a modified anterolateral procedure. From 2004 to 2008, 81 patients seeking elective THRs were randomly assigned into a standard rehabilitation group or an early rehabilitation group. The standard group included restrictions to avoid hip flexion >90° and avoidance of riding in a car for the first postoperative month. The early group had no flexion or car riding restrictions. Forty-three patients were in the standard group and 38 patients were in the early group. There were no significant demographic differences between the 2 groups. All patients completed the Short Form 12-question Health Survey and Harris Hip Score preoperatively and at 4 weeks, 1 month, 3 months, and 1 year postoperatively. The time-points at which the patient first drove and ambulated with a cane, without a cane, and without a limp were also collected. No incidents of dislocation occurred. Patients in the early group were faster to ambulate with only a cane (P=.03), without a cane (P<.001), and without a limp (P=.003). They also drove earlier (P=.02). Pace of recovery was the only significant difference between the 2 groups. The early rehabilitation protocol increases the pace of recovery compared to a pathway with hip precautions without increasing complications.

Total hip replacement (THR) is a common procedure for hip arthritis, which has excellent patient outcomes. The need for THR is increasing every year with 231,000 operations in 2006 in the United States.1 This is a 52% increase from 152,000 THRs in 2000.2 The perioperative care of the patient is coordinated to minimize complications such as dislocation and instability.3 Techniques at the time of surgery that address these issues include selection of the operative approach and closure, component positioning and offset,4 and head size selection.5

The initial 3 months of postoperative care, when the threat of dislocation is greatest, has traditionally included many restrictions on patient activity and range of motion as a preventive measure.6 Some of these guidelines include: limiting flexion of the operative hip to <90°, sleeping in the supine position with an abduction pillow between the legs, using an elevated toilet seat and hip chair, and avoiding automobile transportation to limit excessive bending encountered on entering or exiting the vehicle. Still, the overall rate of dislocation is 2% to 4%.6,7

Recently, Talbot et al8 showed that without hip restrictions there was an early dislocation rate of 0.6% (3/499). However, that study lacked a control group for comparison. Peak et al9 conducted a randomized prospective study and found that when patients were unrestricted there was no increase in the prevalence of postoperative dislocation. Although the patients were only assessed at 6 weeks and 6 months, an increase in patient satisfaction during recovery was shown.9

There is a patient demand to make recovery more rapid and cost-effective while preventing dislocation. The purpose of this randomized investigation is to evaluate the safety and effectiveness of an early rehabilitation protocol for THR patients. It tested the possibility of accelerating patients’ return to activities of daily living by minimizing postoperative hip precautions. The protocol adds to the current literature because patients in the unrestricted group had no restrictions on hip flexion.

Study Protocol

This was a single center, open label, randomized trial. Patients were randomly assigned to either the standard rehabilitation group or the early rehabilitation group prior to their THR. Group assignments were generated by the research coordinator using a random-numbers table and sealed in numbered opaque…

Abstract

Currently, many rehabilitation protocols for total hip replacements (THRs) include activity restrictions to prevent postoperative dislocation. There is increasing demand for more efficient and safe rehabilitation protocols. This randomized prospective study evaluates the need for hip restrictions following a modified anterolateral procedure. From 2004 to 2008, 81 patients seeking elective THRs were randomly assigned into a standard rehabilitation group or an early rehabilitation group. The standard group included restrictions to avoid hip flexion >90° and avoidance of riding in a car for the first postoperative month. The early group had no flexion or car riding restrictions. Forty-three patients were in the standard group and 38 patients were in the early group. There were no significant demographic differences between the 2 groups. All patients completed the Short Form 12-question Health Survey and Harris Hip Score preoperatively and at 4 weeks, 1 month, 3 months, and 1 year postoperatively. The time-points at which the patient first drove and ambulated with a cane, without a cane, and without a limp were also collected. No incidents of dislocation occurred. Patients in the early group were faster to ambulate with only a cane (P=.03), without a cane (P<.001), and without a limp (P=.003). They also drove earlier (P=.02). Pace of recovery was the only significant difference between the 2 groups. The early rehabilitation protocol increases the pace of recovery compared to a pathway with hip precautions without increasing complications.

Total hip replacement (THR) is a common procedure for hip arthritis, which has excellent patient outcomes. The need for THR is increasing every year with 231,000 operations in 2006 in the United States.1 This is a 52% increase from 152,000 THRs in 2000.2 The perioperative care of the patient is coordinated to minimize complications such as dislocation and instability.3 Techniques at the time of surgery that address these issues include selection of the operative approach and closure, component positioning and offset,4 and head size selection.5

The initial 3 months of postoperative care, when the threat of dislocation is greatest, has traditionally included many restrictions on patient activity and range of motion as a preventive measure.6 Some of these guidelines include: limiting flexion of the operative hip to <90°, sleeping in the supine position with an abduction pillow between the legs, using an elevated toilet seat and hip chair, and avoiding automobile transportation to limit excessive bending encountered on entering or exiting the vehicle. Still, the overall rate of dislocation is 2% to 4%.6,7

Recently, Talbot et al8 showed that without hip restrictions there was an early dislocation rate of 0.6% (3/499). However, that study lacked a control group for comparison. Peak et al9 conducted a randomized prospective study and found that when patients were unrestricted there was no increase in the prevalence of postoperative dislocation. Although the patients were only assessed at 6 weeks and 6 months, an increase in patient satisfaction during recovery was shown.9

There is a patient demand to make recovery more rapid and cost-effective while preventing dislocation. The purpose of this randomized investigation is to evaluate the safety and effectiveness of an early rehabilitation protocol for THR patients. It tested the possibility of accelerating patients’ return to activities of daily living by minimizing postoperative hip precautions. The protocol adds to the current literature because patients in the unrestricted group had no restrictions on hip flexion.

Materials and Methods

Study Protocol

This was a single center, open label, randomized trial. Patients were randomly assigned to either the standard rehabilitation group or the early rehabilitation group prior to their THR. Group assignments were generated by the research coordinator using a random-numbers table and sealed in numbered opaque envelopes that were opened on acquisition of informed consent during each patient’s preoperative assessment.

Patients in the standard rehabilitation group were instructed to refrain from bending the operative hip >90°, crossing their legs at the thighs, and riding in a car with the exception of riding home from the hospital. They were to use an elevated toilet seat, sit only on an elevated chair, and sleep flat on their back with a pillow between their legs. These hip restrictions were to be observed for the first postoperative month. Patients had home physical therapy 3 times a week for that month. During the second and third postoperative months, the patients were still limited to flexion <90° and adduction <5°, but were permitted to ride in a car and begin outpatient physical therapy.

Patients in the early rehabilitation group were instructed not to cross their legs at the thighs with otherwise no restrictions. They could bend the hip where they were comfortable and ride in a car without any restrictions. They were to use a regular toilet seat and were permitted to sit on any standard chair. They were able to sleep in any comfortable position without a pillow between their legs. Patients began outpatient physical therapy on hospital discharge.

All patients were required to attend a 1-hour session with a physical therapist preoperatively. In this session, patients were instructed on pre- and postoperative rehabilitation exercises, transfers, and activities of daily living that were consistent with their randomized group assignments. Participants were assessed at a preoperative level approximately 4 weeks preoperatively, and at approximately 1 month, 3 months, and 1 year postoperatively. Patients in the early rehabilitation group were seen for an additional postoperative assessment 2 weeks postoperatively, while patients in the standard rehabilitation group were telephoned for this 2-week evaluation.

During each assessment patients completed a Short Form 12-question Health Questionnaire (SF-12) and a Harris Hip Score. All patients were asked to keep a diary of the number of days until they walked with a cane, walked without a cane, drove, and walked without a limp. The accuracy of this information was verified either by phone interview or by physical assessment at the next scheduled follow-up. Patients were instructed to also write any comments regarding their level of satisfaction and status of recovery. All demographic information was collected during a preoperative medical history and physical examination by a health official.

Exclusion Criteria

Approval from the Institutional Review Board was acquired and all patients were required to provide written informed consent for their involvement in this study. Patients were excluded if they had a previous THR to the operative side, a hearing impairment despite the aid of a hearing device, previous diagnosis with dementia or Alzheimer’s, or no family support at home. Patients were also excluded if they were younger than 21 years, weighed >275 pounds, were unable to ambulate 30 feet without an assistive device preoperatively, or unable to attend postoperative outpatient physical therapy at a designated location.

Patients

Patients were recruited from VSAS Orthopedics, a medical office with physicians specializing in THR and an affiliation to Lehigh Valley Hospital and Health Network. Patients were enrolled from the practice as a representative sample of all patients seeking elective THR from 2004 to 2008.

There were 81 consenting patients in this study. The standard rehabilitation group included 43 patients, 16 women with a mean age of 59.8 years (range, 42-71 years) and a mean body mass index (BMI) of 27.8 kg/m2 (range, 22-35 kg/m2), and 27 men with a mean age of 57.4 years (range, 40-75 years) and a mean BMI of 29.8 kg/m2 (range, 24-37 kg/m2). The early rehabilitation group included 38 patients, 16 women with a mean age of 60.8 years (range, 39-76 years) and a mean BMI of 28.2 kg/m2 (range, 21-40 kg/m2), and 22 men with a mean age of 58.8 years (range, 46-71 years) and a mean BMI of 28.2 kg/m2 (range, 24-34 kg/m2). There were no significant demographic differences based on age (P=.51) or BMI (P=.32) between the 2 groups.

Surgical Technique

All THRs were performed by 1 of the senior authors (P.V. or E.L.). Patients received general endotracheal anesthesia. With the exception of the postoperative rehabilitation protocol, the preoperative, intraoperative, and postoperative management was the same for both groups. Total hip replacement was performed with the patients in a supine position using a modified Hardinge anterolateral surgical technique.10 The components used were selected based on preoperative templating and intraoperative assessment of the acetabular and femoral anatomy combined with patient specific factors such as age, weight, activity level, and functional demands.

Each patient received an uncemented hip replacement. The acetabular components were either a Trilogy with a Longevity neutral liner (Zimmer, Warsaw, Indiana) or Pinnacle with a Marathon neutral liner or Ultamet metal liner (DePuy Johnson and Johnson, Warsaw, Indiana). The components were selected to optimize a 32-mm femoral head on cross-linked polyethylene or to use a metal on metal bearing with a 36- or 40-mm femoral head. The optimal acetabulum position was in 30° to 45° of abduction and 10° of anteversion.

The uncemented femoral components used were either a Modular Medial Lateral Tapered Femur with Kinectiv technology (Zimmer) or a Trilock, Summit, or SROM (DePuy Johnson and Johnson). The femoral component was placed with standard initial reaming and then broaching technique in an optimal 10° of anteversion. Final intraoperative adjustments were made to optimize soft tissue tensioning and hip stability while equaling the leg lengths. This was accomplished by selecting the appropriate femoral head neck length and offset. The hip was then placed through a full range of motion as part of our standard assessment. This included evaluation of maximal flexion, 90° of flexion and 30° of adduction; full extension (20°-30°); 0° of extension and 45° of internal-external rotation; and 0° of extension, 30° of adduction, and 45° of external rotation. After final component placement, closure was performed with absorbable sutures in a layered fashion. All patients had an evaluation of a postoperative radiograph and were made weight bearing as tolerated.

Analysis

All P values <.05 were considered statistically significant. Assuming the risk in the early rehabilitation group to be 0.33%, 53 patients in each group would be required to achieve an 80% power and detect a 3% margin of difference for dislocation prevalence, at an alpha (two-sided) of 0.05.11 The SF-12, Harris Hip Scores, and days until patients walked with a cane, walked without a cane, drove, and walked without limp were evaluated with a two-tailed Student t test. Equal or unequal variance was determined initially with an F-test. Standardized effect size was determined for all statistically significant outcome variables using the mean difference and Hedges’ method for pooled standard deviation.

For interpretation purposes, a successful operative result was considered to be a Harris Hip Score of >80.12

Results

There were no incidents of dislocation in this investigation. All patients in the standard and early rehabilitation groups recovered safely. However, there was a difference in the pace of this process. The results are summarized in the Table. Patients in the early rehabilitation group were faster to ambulate with only a cane (P=.03). This difference was moderately strong with a standardized effect size of 0.48 and power (1-β) of 0.62.

Table: Time-Intervals Mean, Range, and Difference of Means by Group Assignment and Outcome Variable

An overall correlation (r=.6) was found between the number of days walked with and without any assistive equipment; therefore, patients in the early rehabilitation group were also faster to walk without a cane (P<.001, 1-β=0.98). The effect size for this outcome was 0.89, which is noted as strong.

Additionally, patients in the unrestricted group began driving earlier than patients in the restricted group (P=.002, 1-β=0.89). A strong effect size of 0.72 was observed for this variable. Patients in the early group also walked without a limp sooner (P=.003, 1-β=0.90). A strong effect size of 0.70 was established for this variable.

Scores from the Harris Hip Score were tabulated and a small effect size of 0.41 was found for the 3-month assessment (P=.07). All other hip assessments were found to be equivalent across the 2 groups. The Harris Hip Score also showed that at 3 months postoperatively 94.5% (65/73) of all cases performed were at a high grading of success.

Evaluation of the physical component scores and mental component scores of the SF-12 showed no significant differences between the groups at all time intervals. However, the 4-week physical component score yielded an effect size of 0.38 and showed a marginally significant difference where the early rehabilitation patients scored higher (P=.09).

Discussion

This article adds to a small number of existing studies testing postoperative hip restrictions for the prevention of early dislocation. Lifting such restrictions in the early rehabilitation group resulted in an improved speed of recovery. When compared with the control group, patients observing no restrictions were able to walk with a cane and drive earlier. The same group of patients was also able to walk without a limp and without the aid of any assistive devices at an earlier postoperative interval.

On average, patients in both groups were regaining their full range of motion and functions at the same rate as measured by the Harris Hip Score. This assessment tool was chosen because it is a valid and reliable measure of the outcome of a THR.13 It showed no advantage to standard rehabilitation in terms of subsidized pain and that 94.5% of all THRs were conducted at the same success level.

Based on these results, postoperative hip restrictions provide no additional benefit and limit patients from activities that they are capable of doing. These findings demonstrate a faster return to activities of daily living following elective THRs. Without any incidents of dislocation to evaluate, it is not possible to conclude if restrictions are a necessary preventive measure. However, the results may suggest that dislocation can be greatly decreased with proper patient selection and surgical technique alone.14

These conclusions are consistent with previous studies. In their study, Peak et al9 concluded that unrestricted patients reported a significantly higher degree of satisfaction with their recovery. This was not statistically observed when the SF-12 was used in the present study. The SF-12 test was chosen because it has been well-validated as a quality of life assessment tool and its results can be widely compared in the field.15 Patients in the early rehabilitation group were equally as likely to feel limited from performing housework or social activities and suffer emotional strain due to a decreased sense of accomplishment in the months following surgery. The 2 groups were found to recover with the same physical strength and mental stamina as tested by the SF-12.

Although one limitation of the present study is the small sample size, the statistically significant differences had a statistical power of at least 0.08 with the exception of the postoperative time-point when the patients started walking with a cane, which had a power of 0.06. Since there were exclusions to patient enrollment, the generalization of these results may be questioned. It is important to note that the exclusions were imposed in an effort to maximize patient compliance and ability to participate in this investigation. Patients who consented might have been less at-risk than the general population. However, patient characteristics and self-reported physical conditions preoperatively were widely varied and the standard and early rehabilitation groups were not found to differ on any preoperative or postoperative physical, emotional, or demographic components.

Interestingly enough, 1 patient was randomly assigned into the standard group for his left hip and then 1 year later into the early rehabilitation group for his right hip. He included in his diary that “depression was a real issue to contend with in the control group. I was so much happier and the quality of life was so much better in the accelerated group.”

Conclusion

The senior authors (P.V. and E.L.) ended the study before enrolling the target 106 patients to remove the standard hip restrictions and allow all patients to progress to the rapid rehabilitation group without restrictions. Since the conclusion of the trial, there has been no increase in the prevalence of dislocation at this surgical practice. Further protocol adjustments should focus on the best preoperative patient education.7 If standard postoperative restrictions are eliminated, patients must rely on proper preoperative education to evaluate the risks they take with activities of daily living. The performance of a THR with appropriate surgical technique and patient selection can lead to a successful functional recovery at a rapid pace with the elimination of routine hip precautions and restrictions.

References

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Authors

Drs Ververeli and Lebby and Mss Tyler and Fouad are from VSAS Orthopedics and Lehigh Valley Hospital, Allentown, Pennsylvania.

Drs Ververeli and Lebby and Mss Tyler and Fouad have no relevant financial relationships to disclose. This research was supported by a grant from “The Dorothy Rider Pool Health Care Trust” (a non-commercial philanthropic organization fostering clinical research).

Correspondence should be addressed to: Prodromos A. Ververeli, MD, VSAS Orthopedics, 1250 S Cedar Crest Blvd, Allentown, PA 18103.

doi: 10.3928/01477447-20091020-09

10.3928/01477447-20091020-09

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