The effect of early mobility in patients after Total Knee Replacement on hospital length of stay,pain and function: A randomised control trial

Abstract

BACKGROUND: Achieving functional independence as early as possible is a major factor in the management of patients following Total Knee Replacement (TKR). The aim of this study was to evaluate the effect of an early mobilisation program for patients after TKR.

METHODS: This was a prospective randomised controlled study. Twenty patients were allocated to an early mobilization group who mobilised within 4–6 hours after surgery and another twenty to a control group who followed a standard protocol of mobilising within the 24 hours after the surgery. Primary outcome measures were the length of hospital stay and pain scores. Secondary outcomes were the active knee range and the timed up and go (TUG) test as a functional measure.

RESULTS: Pain in the both groups decreased throughout the period however there was no statistically significant difference between groups (p = 0.614). In addition, no significant change in length of stay was noticed between the groups (p = 0.34).

CONCLUSION: The results of this study demonstrate that mobilization within 4–6 hours following TKR does not offer significant advantage over the current standard protocol of mobilizing within 24 hrs of surgery in terms of length of stay, pain or knee range of motion.

Keywords

Early mobility total knee replacement rehabilitation physiotherapy

1 Introduction

Ambulating patients early after Total Knee Replacement (TKR) has been advocated to be best practice for early recovery and return to previous level of function [1]. With ever-increasing healthcare costs, discharge timing of patients is also a crucial factor. The number of days patients stay in an acute inpatient setting is determined many factors including time to achieve independent mobility, types of surgical and anesthetic interventions, medical comorbidities, social issues, and availability of community services packages.

Early mobilisation has been shown to decrease risk of complications, such as deep vein thrombus (DVT), pulmonary embolus (PE), chest infection and urine retention [2, 3]. It has also been shown that early mobilisation in the first 24 hours post-operatively, as part of a structured clinical pathway following knee arthroplasty, reduced hospital stay significantly [4 –7]. However, it is important to note that these studies included early mobilization as part of a multimodal approach including anaesthesia and analgesia optimization.

The current physiotherapy protocol used at Concord Repatriation General Hospital, Sydney, for patients following TKR is to sit out of bed and mobilise on the first day after surgery. This is in keeping with many standardized pathways used at other institutions [5, 8]. Patients then follow a standard physiotherapy protocol until discharge.

The aim of our study was to determine whether mobilising patients following TKR earlier than the standard protocol, i.e. on the day of surgery (approximately 4–6 hours after surgery) would further enhance recovery and reduce length of stay.

2 Methods

2.1 Design

This was a prospective randomized control study. All patients scheduled for TKR were reviewed in pre-admission clinic. The research study was explained to patients, written, informed consent was obtained and they were randomly allocated either into the experimental group or the control group by hat draw by a single author.

2.2 Participants

Patients admitted for primary TKR surgery under a single surgeon (to reduce any variation from surgical component) from our institution over a period of six months, were randomly allocated to either the early mobilisation group (early mobilisation 4–6 hours after operation) or the control group (usual mobilisation within 24 hours after surgery). Patients over the age of 80, patients with major cardiovascular, respiratory diseases and diabetes were excluded from the study.

2.3 Intervention

On the day of surgery, approximately 4–6 hours post-operatively, participants were assessed for their general wellbeing, clinical observations (blood pressure, pulse, respiratory rate, and alertness as per sedation score) and haemoglobin levels. Suitability for those patients in the early mobilisation group to mobilise was decided by the physiotherapist or the senior Orthopaedic nurse in the ward. Participants who satisfied the above assessments were mobilised a short distance, and if able they also sat out of bed for a few hours. After this session, the routine physiotherapy exercise program and mobility progression continued with both early mobilisation and control groups as usual.

2.4 Outcome measures

Our outcome measures included measurement of pain, using the visual analogue scale (VAS), knee range of motion (ROM) which included the active flexion range and the extension range using goniometry, timed up and go test (TUG), which is the time taken in seconds by the patients to get up from a chair and walk 3 m and return to their chair, and the length of hospital stay in number of days. The measurements were taken in a pre-admission clinic, on the day of discharge and at 6-weeks follow-up in the outpatient clinic. Demographic data and the length of stay were obtained from the hospital file.

Primary outcomes were the length of stay and the pain scores. Secondary outcomes were the active knee range and the TUG test as a functional measure.

Clinical indicators for discharge during the period of study were achieving a knee flexion of 80° and extension of 5° short of full extension, the ability to mobilise independently with an aid and to be able to climb stairs.

2.5 Ethics

The study was carried out at Concord Repatriation General Hospital, Sydney under the ethics approval of the Sydney South West Area Health Service Ethics committee.

2.6 Data analysis

Data was analysed using the SPSS package, version 22. Between group differences in the reported outcome measures were analysed by the two-tailed t-test and ANOVA. Length of stay was analysed by the non-parametric Mann-Whitney U test.

3 Results

Forty patients met the selection criteria and were included in the study. Twenty patients were randomized to the early mobility group and twenty to the control group. All patients ranged between the age of 40 and 80 (Table 1). The mean age of both groups was 67.15. All patients were independently mobilising with or without aid prior to TKR.

Table 1
Patient demographics

Early Mobility Group Control Group

Number of patients 20 20

Mean age (range) 65.73 (51–73) 68.88 (56–76)

Male (n) 9 8

Female (n) 11 12

	Early Mobility Group	Control Group
Number of patients	20	20
Mean age (range)	65.73 (51–73)	68.88 (56–76)
Male (n)	9	8
Female (n)	11	12

Five of the patients randomized to the early mobility group were unable to be mobilised in the first 4–6 hours due to nausea or hypotension. Two of the patients in the control group were unable to be mobilised day 1.

VAS pain scores were recorded preoperatively (VAS1), at time of discharge (VAS2) and at 6-weeks post-operatively (VAS3). Pain scores decreased significantly over time for both groups compared to before surgery (VAS1/VAS3 p < 0.001). Pain in the early mobilisation group was higher at all 3 stages compared to the control group, however, this difference was not statistically significant (Table 2).

Table 2

Pain Visual Analogue Scale (VAS) before surgery, at discharge and at 6-week follow-up

VAS	Early Mobility Group	Control Group	P value
	Mean VAS (SD)	Mean VAS (SD)
Before surgery	6.85 (1.99)	6.75 (2.38)	0.905
On discharge	4.82 (2.32)	4.45 (1.96)	0.642
6-week follow up	3.60 (1.58)	3.29 (2.20)	0.704

Knee ROM was measured pre-operatively at the preadmission clinic, at discharge and at 6 week mark using a goniometer (Table 3). The general trend in flexion range in all patients was that it decreased from before surgery to 6 weeks after surgery. This could be explained by post-operative pain levels. However, there was a slight increase in the flexion range at 6-weeks in the early mobility group (97.4°), compared to the control group (92.65°) although this was not statistically significant.

Table 3

Range of movement before surgery, at discharge and at 6-week follow-up

	Flexion			Extension
	Early Mobility	Control	P value	Early Mobility	Control	P value
	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)
Before surgery	107.69 (14.71)	106.65 (13.89)	0.838	8.15 (10.43)	7.95 (6.91)	0.946
On discharge	73.42 (16.05)	81.15 (11.50)	0.123	3.25 (11.40)	8.00 (10.40)	0.237
6-week follow up	97.40 (7.20)	92.65 (26.00)	0.579	6.40 (5.78)	6.96 (6.93)	0.830

Extension in the early mobility group immediately after surgery was 3.25° short of full extension, whereas, the extension in the control group 8.0°. These results immediately post-surgery were not maintained by the early mobility group at the 6-week time point (6.4° for early mobility group and 6.96° for control group). Thus, both early mobility and control group had similar extension range at 6-week time point. None of these differences achieved statistical significance (Table 3).

The TUG test, which was the functional measure for patients undergoing TKR before operation and at 6-weeks, showed no improvement in the early mobility group. The control group at 6-weeks showed slight improvement (15 seconds for control group and 18 seconds for early mobility group) for this measure which did not reach statistical significance (Table 4).

Table 4

Timed up and go (TUG) test before surgery and at 6-week follow-up

	Early Mobility Group	Control Group	P value
	Mean TUG (SD)	Mean TUG (SD)
Before surgery	16.72 (7.50)	20.48 (15.46)	0.423
6-week follow up	18.29 (8.18)	15.02 (3.39)	0.166

Independent T-test analysis indicated that there was no significant difference (p = 0.298) in length of stay between the two groups. The early mobility group stayed 5.8 days (SD = 1.42) and the control group stayed 6.3 days (SD = 1.37).

4 Discussion

This study demonstrated no benefit in mobilizing patients following TKR on the same day rather than after the first 24 hours. This suggests that mobilizing patients earlier may provide no addition benefit and usual care already be optimal as shown in previous studies [7]. Another reason could be that most of the patients in the control group also managed to participate in sitting out of bed and mobilising within the first 24 hour period.

Our institution’s length of stay (LOS) for patients after TKR prior to this study was 7.2 days. Both groups in this study were below this LOS. This could be explained by the exclusion of patients over 80 years old and major medical comorbidities. Other studies have reported the average departmental length of stay as 10.5 days [4]. With a vigorous anaesthetic regime (epidurals and anti-emetic medication in theatre) and mobilisation at four hours post-surgery, they reduced the length of stay to an average of 3.6 days compared to the 6.6 days for the control group [4]. Length of stay is also affected by other factors such as social situations, social support and patient expectations, however, these factors were not controlled in this current study.

A major challenge associated with mobilizing patients immediately post TKR exists when patients are still suffering unpleasant effects from anaesthesia including nausea and vomiting. All patients from our study had general anesthetic. We noted five patients in the early mobility group were unable to be mobilized in the first 4–6 hours due to nausea or hypotension. A regime of combining the early mobility with and individually tailored anaesthetic regime may give improved results and is an area for future research [4].

Our study has specifically looked at the early mobility aspect of the rehabilitation phase of these patients, whereas, other studies have had included other interventions such as continual passive motion [10]. Some studies have used post-operative epidural anaesthesia, which may increase the confidence in mobilisation on the day of surgery and, hence, reduced length of stay in uni-compartment knees [2]. Our patients did not have any alteration to their anaesthesia and or the analgesia part of the management.

Previous studies have reported that a patient’s length of stay can be reduced simply by patients and staff being aware they are part of an early mobility and discharge protocol [4]. In our study, although patients and staff were aware of early mobility and, hence, possible early discharge protocol, it is clear it made no difference to the number of days patients stayed in hospital.

Knee ROM in these two groups of patients was also not significantly different, supporting the conclusion that there may not be enough delay in mobilising between the two groups. ROM is an important indicator of outcome and previous research has reported that knee range during the early periods after TKR is a predictor of long term range [9]. These authors also found that pain and function for these patients were directly associated with ROM measured in the sub-acute phase [9]. Further there were no significant differences in pain scores (VAS) between the two groups at any stage of the study. This is an important finding, as this current study did not alter any of the analgesic and anaesthetic components of the surgery. Despite being mobilized earlier, the early mobility group did not report higher pain scores.

TUG has been reported to have predictability of Western Ontario and McMaster Osteoarthritis Index (WOMAC) function in the TKR population [1]. They also report that TUG is a reliable indicator for self-reported function in these patients. Our control group performed slightly better than the early mobilistion group with the TUG test although these results did not reach statistical significance.

5 Conclusion

This study has demonstrated that an early mobility protocol on the same day of surgery for patients after TKR surgery may not offer any advantage over usual care and does not reduce hospital LOS. Although patients did not report higher pain scores being mobilized on the same day after TKR, side effects of anaesthetic and hypotension may inhibit their ability to safely do so.

Conflict of interest

None.

References

, Naylor

, Harris

, Crosbie

, Yeo

AET

. The six-minuted walk test is an excellent predictor of function after total knee arthroplasty. BMC Musculoskeletal Disorder 2013;14:145.

Beard

, Murray

, Rees

, Price

, Dodd

CAF

. Accelerated recovery for unicompartmental knee replacement- a feasibility study. The Knee 2002;9:221–4.

Pearse

, Caldwell

, Lockwood

, hollard

. Early mobilization after conventional knee replacement may reduce the risk of post-operative venous thromboembolism. J Bone Joint Surg Br 2007;89B(3):316–22.

Issac

, Falode

, Liu

, I’Anson

, Dillow

, Gill

. Accelerated rehabilitation after total knee replacement. The Knee 2005;12:346–50.

Dowsey

, Kilgour

, Santamaria

, Choong

. Clinical pathways in hip and knee arthroplasty: A prospective randomized controlled study. Med J Aust 1999;170(2):59–62.

Reily

, Beard

, Barker

, Dodd

, Price Murray

. Efficacy of an accelerated recovery protocol for Oxford Unicompartmental knee arthroplasty. Randomised controlled trial. The Knee 2005;12:351–7.

Renkawitz

, Reider

, Handel. Comparison of two accelerated clinical pathways- after total knee replacement how fast can we really go. Clin Rehabil 2010;24(3):230–9.

Pearson

, Moraw

, Maddern

. Clinical pathway management of total knee arthroplasty: A retrospective comparative study. Aust N Z J Surg 2000;70(5):351–4.

Naylor

, Ko

, Rougellis

, et al. Is discharge knee range of motion a useful and relevant clinical indicator after total knee replacement? Part I, J Eval Clin Pract 2012;18:652–8.

10.

Harvey

, Brosseau

, Herbert

. Continuous passive motion following total knee arthroplasty in people with arthritis. Cochrane Database of Systematic Reviews 2014;2. Art. No.: CD004260. DOI: 10.1002/14651858.CD004260.pub3