Home-Based vs. Conventional Rehabilitation Following Total Knee Arthroplasty

Abstract

Objective: The aim of this meta-analysis was to investigate whether home-based physical therapy (HPT) is as safe and effective as the conventional inpatient/outpatient physical therapy (CPT) after total knee arthroplasty (TKA). Methods: Three databases (PubMed, Web of Science, and Cochrane) were systematically searched on 8 January 2024. Randomized controlled trials (RCTs) comparing HPT with CPT following TKA were included. The outcomes included Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS), 6 min walking test, range of motion (ROM), 36-Item Short Form Survey (SF-36), and visual analogue scale (VAS) for pain, and were analyzed at short-term (≤12 weeks) and mid/long-term follow-ups (>12 weeks). Results: Twenty RCTs (3706 patients) were included. Both groups experienced significant improvements, but no differences emerged when comparing all analyzed outcomes. WOMAC improvement was 36.2 points with HPT (p < 0.0001) vs. 39.2 with CPT (p < 0.0001); KOOS increased by 24.8 points with HPT (p < 0.0001) vs. 25.2 points with CPT (p < 0.0001); OKS improved by 16.1 points with HPT (p < 0.0001) vs. 16.3 points with CPT (p < 0.0001); ROM improved by 6.3° with HPT (p = n.s.) vs. 7.7° with CPT (p = 0.029); SF-36 improved by 3.3 points with HPT (p = n.s) vs. 7.4 points with CPT (p = n.s.); and VAS pain decreased by 2.5 points with HPT (p < 0.0001) vs. 3.0 points with CPT (p < 0.0001). Conclusions: HPT is a valid option for the post-operative rehabilitation of patients undergoing TKA, leading to results similar to CPT. This questions the need for a more complex and expensive management of these patients, considering the additional HPT benefits of healthcare cost reductions, early patient discharge, and less in-person physical therapy sessions, with equal patient final satisfaction. While this review offers a comprehensive representation of numerous studies, the research underlines significant heterogeneity in the reported data, thereby diminishing the overall robustness of the analysis, and future studies are needed to confirm the study results.

1. Introduction

Total knee arthroplasty (TKA) is one of the most performed orthopedic interventions worldwide, with figures estimated to grow further in the future due to the longer life expectancy of the general population and the consequent foreseen rise in osteoarthritis (OA) prevalence [1,2,3]. The TKA objective is to restore knee joint function, improve patients’ clinical outcomes and quality of life, and provide ways to return to daily activities with little or no pain. To this aim, crucial aspects influencing TKA results include accurate patient selection, along with adequate management after surgery [4].

Post-operative TKA physical therapy (PT) is essential for restoring physical function, reducing knee pain, regaining strength, and enabling patients to return to their daily tasks and work after surgery [5]. With the aging population and the rising number of TKA procedures, expected to reach 3.48 million annually by 2030, the optimization the post-operative PT approaches has become pivotal. Rehabilitative interventions can be broadly categorized into conventional in-person inpatient/outpatient PT (CPT) and home-based PT (HPT) [4]. CPT typically involves early inpatient mobilization in the hospital during the initial post-operative days to achieve functional independence and ensure safe discharge, followed by outpatient physiotherapy [6,7]. However, these programs place significant demands on healthcare systems from a financial perspective. Moreover, treatment delays due to PT waiting lists or individual post-operative physical conditions, particularly in elderly patients, can hinder adherence to PT, resulting in less satisfactory outcomes and decreased patient motivation [8]. As an alternative, HPT has been proposed to address these challenges by offering a cost-effective and patient-centered approach [9,10]. HPT enables early discharge, fosters better compliance, and enhances patient satisfaction, especially for motivated individuals who adhere more consistently to prescribed home-based rehabilitation protocols [11]. This approach requires fewer resources and provides a simpler, more feasible setting for recovery, aligning with the needs of healthcare systems and patients alike [12]. Nonetheless, defining the optimal PT strategy remains complex and must account for healthcare system constraints, patient characteristics, and specific rehabilitation needs [8,13]. In light of these considerations, different strategies for post-operative PT should be carefully evaluated. HPT stands out as a promising option, particularly for patients who are likely to comply with rehabilitation instructions, but a broader applicability of this method depends on proper guidance and support. Tailoring PT interventions to individual patient profiles is essential to maximize the outcomes and address the multifaceted challenges associated with post-operative care. Despite the significant interest in the topic, the current literature lacks consensus regarding the optimal type of rehabilitation to recommend for patients following knee replacement surgery [14,15]. Accordingly, this study seeks to address this gap by comparing the two primary rehabilitative approaches, thereby providing a clinically relevant contribution to the existing body of knowledge.

The aim of this systematic review and meta-analysis was to compare HPT with CPT to investigate whether a home-based rehabilitative approach is as safe and effective as the conventional in-person inpatient/outpatient physical therapy intervention to rehabilitate patients after TKA.

2. Materials and Methods

A review protocol was created based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement (www.prisma-statement.org, accessed on 1 January 2024). The study was registered on PROSPERO (CRD42023395811). A literature search was performed in three bibliographic databases (PubMed, Web of Science, and Cochrane) from inception up to 8 January 2024. The following research terms were used: “(total knee arthroplasty OR TKA OR total knee replacement OR TKR OR knee prosthesis) AND (rehabilitation OR physioterap* OR exercise OR physical therapy) AND (home-based OR home OR self)” with the goal to retrieve the highest possible number of published studies on the researched topic. The inclusion criteria were randomized control trials (RCTs) addressing HPT vs. CPT following TKA. Non-RCTs, pre-clinical, ex vivo studies, and review articles were excluded (

Table 1. Inclusion and exclusion criteria for study selection.

Inclusion Criteria	Exclusion Criteria
Studies comparing patients that underwent TKA with home-based PT versus inpatient and/or outpatient PT	Non-randomized studies
Randomized controlled studies	Expert opinions, systematic reviews, and meta-analyses
Human studies	Pre-clinical or ex vivo studies

). The reference lists from the selected studies and from the systematic reviews found with the first and second screening were also screened, and all the selected studies were included in the quantitative data synthesis (Figure 1). The authors considered an HPT program only if it included a home-based rehabilitation plan with fewer than three physiotherapist-supervised sessions.

2.1. Data Extraction

Two independent reviewers (LMO and AS) screened all the articles per title, abstract, and the full text to assess whether they met the inclusion criteria (Figure 1). In case of disagreement between the two reviewers, a third reviewer (SN) was consulted to reach a consensus. The following data were independently extracted: author, year of publication, country, number of patients, demographic characteristics, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS), Six-Minute Walking Test (6MWT), Range Of Motion (ROM), 36-Item Short Form Survey (SF-36), and the Visual Analogic Scale (VAS) for pain (see Figure A1).

The overall results were analyzed, pooling the final scores of the studies to investigate the overall outcome and comparing results based on the rehabilitation phase, considering ≤12 weeks as short-term results and >12 weeks as mid/long-term results after TKA.

2.2. Risk of Bias

The Cochrane Collaboration Risk of Bias tool for randomized trials Version 2 (RoB 2) [16] was used to evaluate risk of bias and quality of the included RCTs. It evaluates the following variables: random allocation sequence, allocation concealment, blinding (of patients, therapists, and outcome assessors), attrition (loss to follow-up and intention-to-treat analysis), and selective outcome reporting. Assessment of risk of bias and quality of evidence was independently completed by two authors (LMO and AS) for all outcomes. In case of disagreement, a third author (SN) solved any possible discrepancy.

2.3. Statistical Analysis

The statistical analysis and the forest plot were carried out using the Meta XL tool for Microsoft Excel by an independent professional statistician. The analysis was carried out using Random effects (DerSimonian and Laird) for weighted mean difference in the continuous variables; the Mantel–Haenszel method was used to provide pooled incidence rates across the studies. A statistical test for heterogeneity was first conducted with the Cochran Q statistic and I² metric and the presence of significant heterogeneity was considered with I² values ≥ 25%. When no heterogeneity was found with I² < 25%, a fixed effect model was used to estimate the expected values and 95% Cis, otherwise, a random-effect model was applied, and an I² metric was evaluated for the random effect to check the correction of heterogeneity. The studies rate confidence intervals were carried out using the continuity-corrected Wilson interval.

3. Results

A total of 3435 articles were retrieved; after screening the titles, abstracts, and full texts, 20 RCTs were included in the systematic review and meta-analysis. The studies analyzed 3706 patients with a mean age of 67.8 ± 7.5 years, who underwent TKA and were subsequently randomized to undergo different PT protocols: 1853 (mean age 67.0 ± 7.7 years, 68.7% women, 31.3% men) underwent HPT protocols after being discharged whereas 1853 patients (mean age 67.6 ± 7.6 years, 68.2% women, 31.8% men) received CPT. The mean follow-up time was 7.8 ± 5.7 months. A detailed description of the PT protocols delivered for each group is reported in

Table 2. Details of the included studies. F-up: follow-up, n°: number of patients, h: hour, w: weeks, m: months, y: years, WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index, OKS: Oxford Knee Score, KOOS: Knee injury and Osteoarthritis Outcome Score, 6MWT: Six-Minute Walking Test, ROM: Range Of Motion, VAS: Visual Analogic Scale for pain, SF-36: 36-Item Short Form Survey, PT: Physical therapy, CPT: conventional PT, HPT: home-based PT.

Author, Year	Country	Journal	Max f-up	Outcomes	n°	PT Description	Inclusion Criteria	Exclusion Criteria
Mitchell et al. 2005 [17]	UK	Journal of Evaluation in Clinical Practice	12 w	WOMAC SF-36	57	Minimum of three pre-operative visits and up to six post-discharge visits. Physiotherapists visiting outpatient knee classes, in addition to two in-house training sessions (1 h each).	Primary unilateral TKA for OA.	Revision, bilateral or unicondylar TKA, TKA following severe trauma, serious comorbidity or terminal illness.
					57	Post-discharge only. Group exercises plus individual treatment. Knee classes of 7–10 patients in the gymnasium; usually one–two times/w.
Kramer et al. 2003 [18]	Canada	Clinical Orthopaedics and Related Research	1 y	WOMAC ROM SF-36 6MWT	80	Home-based PT monitored by periodic telephone calls.	Primary unilateral TKA for OA, at least 90° active knee flexion ROM before surgery, functional hip on the operative side.	Rheumatoid arthritis, major neurologic conditions.
					80	Standard inpatient PT twice daily, for 20 min.
Han et al. 2015 [19]	Australia	Arthritis Care & Research	6 w	WOMAC ROM	194	Ten res of each exercise, three times/day. One clinic-based appointment in the first w after hospital discharge Weekly telephone calls to monitor adherence.	Age between 45 and 75 years. Unilateral or bilateral primary TKA.	Previous replacement or tibial osteotomy on the same knee, previous lower extremity joint replacement within the last 6 months or the next 12 months, comorbidity that precluded exercise at 50–60% maximum heart rate, rheumatoid arthritis, major neurologic conditions.
					196	Clinic-based outpatient PT for 6 w after discharge.
.Minns Lowe et al. 2012 [20]	UK	Clinical Rehabilitation	1 y	OKS KOOS	56	Two post-discharge home visits (within 2 weeks, then 6–8 weeks from discharge).	Primary unilateral TKA for OA.	Bilateral/unicompartmental prosthesis, minimally invasive surgery, planned further joint surgery within 12 months, inflammatory arthritis, comorbidities preventing participation.
					51	Conventional PT treatment.
Naylor et al. 2012 [21]	Australia	Journal of Evaluation in Clinical Practice	<12 w	ROM OKS	20	Six-week monitored home-based PT.	Unilateral or bilateral primary TKA.	Beta-blockers, cardiac pacemakers and residency beyond the geographical catchment area of the participating hospitals.
					22	Six-week group-based PT.
Shepperd et al. 1998 [22]	UK	General practice	12 w	Rehab costs	46	Home care.	Under 60 years.	NR.
					39	Conventional PT in the hospital.
Piqueras et al. 2013 [23]	Spain	Journal Rehabilitation Medicine	12 w	ROM VAS WOMAC	68	One-hour interactive virtual software-hardware platform sessions for 10 days.	Successful primary TKA surgery Post-TKA active range of motion: flexion 80° and extension −10°, without signs of stiffness.	Comorbidities that may influence the rehabilitation process, local or systemic complication (e.g., surgical wound infection, suspicion of deep vein thrombosis) in the three-month follow-up.
					65	One-hour sessions for 10 days.
Madsen et al. 2013 [24]	Denmark	Danish Medicine Journal	26 w	ROM OKS SF-36	32	Home exercises plus one–two planned visited with a local physiotherapist	Age of 18 years or more. Primary TKA for osteoarthritis.	Neurodegenerative diseases, knee infection, loosening or embolism, problems related to mobility, muscle strength or excessive pain preventing the patient from following the rehabilitation program.
					36	Two sessions/week for 6 weeks, combined with home exercises.
Ko et al. 2013 [25]	Australia	Journal of Bone and Joint Surgery	1 y	OKS WOMAC ROM 6MWT	80	HPT for 6 weeks.	Primary unilateral or simultaneous bilateral TKA.	Severe respiratory or cardiac comorbidity, weight-bearing restricted, or deep site infection or joint instability was diagnosed.
					85	1:1 CPT for 6 weeks.
					84	Group-based PT sessions for 6 weeks
Barker et al. 2021 [26]	UK	British Medicine Journal Open Access	1 y	OKS KOOS (Qol) VAS	309	HPT program delivered by rehabilitation assistants with supervision from qualified therapists.	TKA	Any major perioperative complications, further surgery planned within the next 12 months and absolute contraindications to exercise.
					312	Usual care: outpatient CPT.
Naylor et al. 2021 [27]	Australia	American College of Rheumatology	10 w	KOOS (pain) OKS 6MWT	58	Three group-based outpatient CPT sessions between 2 and 10 w after surgery. The participants were expected to perform daily exercises at home.	Unilateral or bilateral primary TKA	Presence of beta-blockers, cardiac pacemakers and residency beyond the geographical catchment area of the participating hospitals.
					55	Daily therapy comprising 1–1.5 h of 1:1 CPT and another 1–1.5 h of class-based session later in the day in an inpatient facility.
Xu et al. 2021 [28]	China	Journal of Orthopaedic Surgery and Research	1 y	ROM WOMAC VAS	55	Doctors guided patients through phone calls or WeChat to correct patient actions and answer patient questions once/week.	Primary TKA for OA	Patients <40 or >80 years, revision surgery, lower limb ischemia, acute trauma or fracture, systemic or neuromuscular diseases, intellectual disorders.
					51	Twenty-four sessions of a CPT program, 2 days/week for the first 7 weeks, followed by 1 day/m for the remaining 10 months.
Hamilton et al. 2020 [29]	UK	British Medicine Journal Open Access	1 y	OKS VAS	171	CPT review followed by a HPT regimen.	TKA for OA in patients defined as at risk of a poor outcome	No expectation of mobilizing postoperatively, complex revision procedures
					163	Eighteen sessions of CPT. Six therapists led outpatient CPT.
Correia et al. 2018 [30]	Portugal	Scientific Report	6 w	KOOS ROM	38	HPT with real-time feedback on performance through a mobile app. Two-week program after surgery (10 sessions).	Age ≥ 18 years, TKA for OA, ability to walk unaided.	Revision TKA, contralateral hip/knee OA, respiratory, cardiac, metabolic or other condition incompatible with at least 30 min of light to moderate physical activity, major medical complications occurring after surgery.
					31	Conventional CPT two-week program (10 sessions).
Fleischman et al. 2018 [31]	USA	Clinical Orthopaedics and related Research	6 m	KOOS ROM	97	Unsupervised home exercise using a printed paper manual, two–three sessions/week for 4–8 weeks.	Age ≥ 18 years, primary unilateral TKA for OA.	Preoperative knee flexion <90°, dysfunction in a hip or the contralateral knee, revision or conversion TKA.
					96	Interactive web-based platform two-three sessions/week for 4–8 weeks.
					97	Outpatient CPT two–three sessions/week for 4–8 weeks.
					24
Prvu Bettger et al. 2020 [32]	USA	Journal of Bone and Joint Surgery	12 w	KOOS VAS	151	Cloud-based virtual telehealth system (VERA) with 3D tracking technology, an avatar (digitally simulated coach), visual and audible instructions and immediate feedback on exercise quality. The frequency and duration of use were unrestricted.	Unilateral TKA.	Bilateral or staged bilateral TKA, nursing home prior to surgery.
					153	Conventional CPT.
Bini et al. 2017 [33]	USA	Journal of Telemedicine and Telecare	24 w	KOOS VAS	13	Asynchronous video application on a mobile device.	Unilateral TKA, age ≤ 75 y, home access to the internet and email.	NR.
					15	Conventional CPT.
Pua, 2023 [34]	Singapore		24w	KOOS Pain ROM SF	56	Telemonitoring self-directed rehabilitation.	Primary unilateral TKA, age > 45 y.	Had significant back or other non-knee pain, had a previous history of stroke and other major neurological conditions, or had an intention to transfer to step-down care facilities post- operatively.
		Osteoarthritis and Cartilage			58	Physical therapy department approximately two weeks and after conventional SPT.
Büker et al. 2014 [35]	Turkey	Journal Physical Therapy Science	2 y	VAS ROM WOMAC SF-36	16	Standardized home program groups.	TKA.	NR.
					18	Supervised CPT.
Crawford et al. 2021 [36]	USA	The Journal Bone & Joint Journal	12 w	KOOS ROM	160	Mymobility with Apple Watch platform. Six–eight exercises, performed three times/day, 6 days/week for 6 weeks.	Age ≥18 y, unilateral primary TKA, Apple iPhone (Apple, Cupertino, CA, USA) and Apple Watch, no more than a single walking stick/single crutch for assistance preoperatively.	Protected populations, inflammatory arthropathies, other surgical intervention that would conflict with the study, simultaneous or staged bilateral knee arthroplasties < 90 days apart.
					185	Conventional CPT.

.

3.1. Analysis Baseline to Mid/Long-Term

The WOMAC score was reported in six studies [17,18,19,25,28,35]. The mean improvement from baseline was 36.2 points in the HPT group (95% C.I. 21.4–−51.0, SE 7.6, p < 0.0001) and 39.2 points in the CPT group (95% C.I. 20.3–−58.0, SE 9.6, p < 0.0001). The comparison between the groups showed no differences in the overall WOMAC results and mean WOMAC improvements (both n.s.). The analysis of “pain” and “function” scales of the WOMAC score showed the same results, with a significant improvement from baseline for both PT approaches (p < 0.001) with no difference between treatments (n.s.). Figure 2 shows, graphically, the WOMAC total results in Figure 2a, the WOMAC “pain” results in Figure 2b, and the WOMAC “function” results in Figure 2c.

The KOOS was retrieved in nine studies [20,26,27,30,31,32,33,34,36]. The mean improvement from baseline resulted in 24.8 points in the HPT group (95% C.I. 17.1–−32.4, SE 3.9, p < 0.0001) and 25.2 points in the CPT group (95% C.I. 17.1–−32.6, SE 3.8, p < 0.0001). The inter-groups’ comparison showed no differences in the overall KOOS values and the mean KOOS improvements (both n.s.). The analysis of “pain” and “quality of life” KOOS categories showed comparable results, with a significant improvement from baseline for both rehabilitation approaches (p < 0.01) with no difference between treatments (n.s.). Figure 2 shows graphically the KOOS total results in Figure 2d, the KOOS “pain” results in Figure 2e, and the KOOS “quality of life” results in Figure 2f.

The OKS was used in six studies [20,24,25,26,27,29]. The mean improvement from the baseline was 16.1 points in the HPT group (95% C.I. 12.7–−19.5, SE 1.7, p < 0.0001) and 16.3 points in the CPT group (95% C.I. 11.9–−20.7, SE 2.2, p < 0.0001). The comparison between the groups showed no differences in the overall OKS values and mean OKS improvements between the two treatments (both n.s.). Figure 2g shows, graphically, the OKS results.

The VAS pain scores were reported in eight studies [26,28,29,32,33,34,35,37]. The mean improvement from baseline was 2.5 points in the HPT group (95% C.I. −3.9–−1.1, SE 0.7, p < 0.0001) and 3.0 points in the CPT group (95% C.I. −4.6–−1.3, SE 0.8, p < 0.0001). The comparison between the groups showed no differences in the mean VAS improvements and VAS values reached after surgery (both n.s.). Figure 2h shows, graphically, the SF-36 results. Five studies reported the SF-36 questionnaire results [18,24,25,34,35]. The mean improvement from the baseline was 3.3 points in the HPT group (95% C.I. −8.3–−14.9, SE 5.9, n.s) and 7.5 points in the CPT group (95% C.I. −6.3–−21.2, SE 7.0, n.s.). The inter-groups’ comparison proved no differences in the mean SF-36 improvements and SF-36 values reached after surgery (both n.s.). Figure 2i shows, graphically, the VAS results.

The 6MWT was reported in three studies [18,25,27], and meta-analysis was not feasible due to the lack of sufficient data.

Flexion ROM changes were indicated in seven studies, of which six documented both pre-operative and post-operative values [25,28,30,31,35,36]. The mean improvement from the baseline was 6.3 degrees in the HPT group (95% C.I. −2.9–−15.6, SE 4.7, n.s.) and 7.7 degrees in the CPT group (95% C.I. 1–−14.4, SE 3.4, p = 0.029). Comparing data between the groups led to no differences in the overall flexion improvements and flexion values at the follow-up (both n.s.). Figure 3a shows, graphically, the flexion ROM results at the midlong follow-up.

3.2. Analysis Baseline to Short-Term and Short- to Mid/Long-Term

The analysis of ≤12 weeks (short-term follow-up) vs. >12 weeks (mid/long-term follow-up) results was feasible for KOOS, OKS, flexion ROM, and SF36.

The KOOS values were reported in seven studies [20,30,31,32,33,34,36]. At the short-term follow-up, the KOOS values showed a mean improvement from the baseline of 13.9 points in the HPT group (95% C.I. 1.8–25.9, SE 6.2, p = 0.007) and 11.4 points in the CPT group (95% C.I. 0.2–22.9, SE 5.9, p = 0.027) (Figure 4a shows, graphically, the KOOS results. From the short- to mid/long-term follow-ups, the KOOS values further improved by 9.3 points in the HPT group (95% C.I. 3.9–14.6, SE 2.7, p < 0.0001) and 8.1 points in the CPT group (95% C.I. 3.7–15.6, SE 3.8, p < 0.05). The comparison between the groups showed no statistically significant difference in mean KOOS improvements and KOOS values both at short and final follow-ups (both n.s.).

The OKS values were indicated in six studies [20,24,25,26,27,29]. At the short-term follow-up, the OKS values showed a mean improvement from baseline of 12.7 points in the HPT group (95% C.I. 9.7–15.7, SE 1.6, p < 0.0001) and 13.6 points in the CPT group (95% C.I. 9.9–17.3, SE 1.9, p < 0.0001). The comparison between the groups showed statistically higher OKS short-term absolute score values in the CPT group compared to the HPT group (p = 0.025), but the difference in the improvement from baseline did not reach statistical significance (n.s.). From the short- to mid/long-term follow-ups, the OKS values further improved by 3.8 points in the HPT group (95% C.I. 0.1–6.9, SE 1.6, p = 0.02) and 3.1 points in the CPT group (95% C.I. −0.2–6.3, SE 1.7, p = 0.06). At the mid/long-term follow-up, the inter-group comparison showed no difference in the mean OKS improvements and OKS values (both n.s.).

The SF-36 scores were available in five studies [17,18,24,25,34]. At the short-term follow-up, the SF-36 values showed an improvement from baseline of 9.6 points in the HPT group (95% C.I. 1.0–20.3, SE 5.4, n.s.) and 4.7 points in the CPT group (95% C.I. 2.9–12.3, SE 3.9, n.s.). Figure 4b shows graphically the SF-36 results. From the short– to mid/long-term follow-up, the SF-36 values did not significantly improve (n.s.). The comparison between the groups showed no differences in the mean SF-36 improvements and in the SF-36 values both at short- and mid/long-term follow-ups (both n.s.).

The flexion ROM values were retrieved in seven studies [18,25,28,30,31,34,35,36]. At the short-term follow-up, the flexion showed an improvement from the baseline of 2.0 degrees in the HPT group (95% C.I. −6.6–2.6, SE 5.3, n.s.) and 0.2 degrees in the CPT group (95% C.I. −8.9–9.3, SE 4.6, n.s.). Figure 3b shows, graphically, the flexion ROM results at the early follow-up. From the short- to mid/long-term follow-up, the flexion ROM further gained 9.5 degrees in the HPT group (95% C.I. −12.9–6.0, SE 1.7, p < 0.0001) and 9.4 degrees in the CPT group (95% C.I. −16.7–2.3, SE 3.7, p < 0.0001). The comparison between the groups showed no differences in the flexion ROM values at the short- and mid/long-term follow-ups (n.s.).

3.3. Risk of Bias

The evaluation of the risk of bias using the Cochrane RoB 2 tool showed a heterogeneous quality of the studies, with eight papers falling in the “low-risk” category, eight in the “Some concerns” category, and five in the “high-risk” category (see

Table A1. Outcomes analyzed to compare conventional inpatient/outpatient versus home-based physical therapy approaches after total knee arthroplasty. WOMAC—Western Ontario and McMaster Universities Osteoarthritis Index, KOOS—Knee injury and Osteoarthritis Outcome Score, OKS—Oxford Knee Score, 6MWT—Six Minute Walking Test, ROM—Range Of Motion, SF-36—36-Item Short Form Survey, Pain VAS—Visual Analogic Scale for pain.

WOMAC score	It is widely used in the evaluation of hip and knee OA, as well as for the evaluation of the results after TKA [2,29]. It is a self-administered questionnaire comprised by 24 items organized into 3 subscales: Pain (5 items), Stiffness (2 items), and Physical Function (17 items). The questions are scored on a scale of 0–4, which correspond to: None (0), Mild (1), Moderate (2), Severe (3), and Extreme (4). The scores for each subscale are combined with a possible score range of 0–20 for Pain, 0–8 for Stiffness, and 0–68 for Physical Function. This is then transformed into a 0–100 scale, with zero representing no knee difficulties and 100 major knee complains.
KOOS	It is a knee-specific patient-reported outcome measure (PRO) developed to assess the patients’ opinion regarding their knee and associated problems. It holds 42 items in 5 separately scored subscales; Pain, other Symptoms, Function in daily living (ADL), Function in Sport and Recreation (Sport/Rec), and knee-related Quality of Life (QOL). Its final score is expressed from 0 to 100, with 0 meaning severe problems and on the other hand 100 no issues.
OKS	It is a 12-item PRO conceived to specifically assess the level of function, activities of daily living and how they have been affected by pain over the preceding four weeks in TKA patients. In its 0–4 scoring system, 4 is the best outcome and total scores range from 0 (poorest function) to 48 (maximal function).
6MWT	It is an aerobic capacity sub-maximal test developed by the American Thoracic Society and used to determine an individual’s exercise tolerance. The total distance covered over a time of 6 min is considered as the outcome by which to compare changes in performance capacity.
SF-36	It is a physical health measure comprising 36 items that assess patients’ health status and its impact on their lives. It is composed of eight multi-item scales (Physical Functioning, Role-Physical, Bodily Pain, General Health, Vitality, Social Functioning, Role-Emotional, Mental Health), with scores for each of such scales ranging from 0 to 100. Higher scores indicate higher quality of life with a range from 0 (worst) to 100 (best).
Pain VAS	It is a unidimensional measure of pain intensity consisting in an 11-point numerical scale ranging from 0 (e.g., “no pain”) to 10 (e.g., worst imaginable pain).

).

4. Discussion

The main finding of this meta-analysis is that HPT is as effective as CPT at both short- and mid/long-term follow-ups, thus endorsing the home-based approach after TKA surgery.

HPT approaches proved to be suitable for different orthopedic surgical procedures, such as anterior cruciate ligament reconstruction [38], meniscectomies [39], and other arthroscopic treatments [40], with promising findings also when compared to traditional CPT following TKA [5,19,41]. The results of this meta-analysis build upon the earlier reports on the benefits of this approach by confirming the potential of the home-based management to provide satisfactory outcomes also for the rehabilitation of a complex intervention like TKA. The relevance of this result is strengthened by the high number of available RCTs and by the depth of the analysis covering short- and mid/long-term follow-up results, pivotal for patients undergoing such invasive surgical procedure. PT is a long process that leads to gradual improvement over time, with patients reaching progressive functional milestones at different time points until the results can be considered stable. A main finding of this meta-analysis is that no differences could be detected even in the earliest follow-up, where the benefits of a closer inpatient/outpatient management could be expected by fostering a faster recovery when compared to patients handling the post-operative phase in a home-based setting.

The early phase is key, especially for ROM recovery, which could affect the eventual TKA outcome. Knee ROM is an objective variable used to assess final flexion/extension after TKA and hence to evaluate the appropriate function of a prosthetic joint. Most activities of daily living can be comfortably performed with a post-operative maximal knee flexion between 100° and 120°. Given the unsupervised HPT approach described in the majority of the included RCTs, with unclear recovery goals and patients’ potential lower exercise adherence if not adequately guided to overcome their limitations [8], a possible impact on their ability to reach the required ROM for a positive clinical outcome could have been expected. This was not confirmed by this meta-analysis. In fact, in line with the good results obtained by both the PT approaches at the early time point, also the mid/long-term ROM results were consistent, with HPT showing the same overall objective values as CPT.

The analysis of all the analyzed clinical subjective outcomes (WOMAC, KOOS, OKS, SF36, and pain VAS), which are of utmost relevance for the patient, showed no differences between CPT and HPT either. Overall, patients in both groups experienced significant improvements compared to their pre-surgical status, with no inter-groups statistically significant differences in patient-reported functional or clinical outcomes at the mid/long-term follow-ups. The questionnaires covered all the aspects that must be taken into account after TKA: knee function, pain, patients’ perceived quality of life, and return to daily activities. To understand whether the two PT approaches carried different benefits in the early recovery phase, a sub-analysis for the patient-reported outcome measures was performed on the first 12 postoperative weeks. This evaluation confirmed comparable results between CPT and HPT groups in terms of KOOS and SF-36 scores, with only one difference detected for the OKS, where CPT showed statistically significant better results compared to the HPT group. Nonetheless, no statistically significant difference was detected in terms of mean OKS improvements between the two groups, and the clinical significance of the documented values is of questionable clinical relevance, thus not translating in any significant difference between CPT and HPT at the mid/long-term follow-up.

This may have important repercussions from a healthcare system perspective. Fusco et al. highlighted that HPT resulted in an average saving of 18% per patient compared to conventional rehabilitation [42]. Another study, by Summers et al., showed that HPT exhibited a remarkable cost-saving advantage of USD 2460 per patient compared to standard therapy [43]. Based on other literature findings, HPT can achieve cost reductions of up to 20–40% compared to traditional in-person physiotherapy for patients undergoing TKA. Considering the projected increase in TKA procedures due to population aging, even the minimum cost savings per patient would be amplified significantly, leading to substantial overall healthcare savings [42,44]. Of note, most of the studies on the home-based approach excluded patients with severe comorbidities, which underlines the importance of the appropriate indication of properly selected patients to be successful [24,34,45]. These patients can be instructed on how to perform a well-planned and customized HPT program, with dedicated follow-ups performed when necessary. While providing overall comparable clinical and functional outcomes could help face the globally increasing pressure on the healthcare systems, favoring an optimized utilization of the already limited resources to cover the overall demands of the population.

The strength of the findings supporting HPT relies on a meta-analysis study design with the inclusion of RCTs only, including a large number of patients. However, some relevant limitations are still present. Firstly, even though this review is a comprehensive representation of many articles, the included studies presented a significant heterogeneity of the reported data, as pointed out by the evaluation of the risk of bias, thus reducing the overall significance of each analysis and therefore suggesting a cautious interpretation. The patient characteristics (e.g., age, body mass index, disease severity, etc.) may have differed between the included studies, limiting the reliability of the conclusions, although, concurrently, most of the HPT studies excluded patients with severe comorbidities limiting the impact of these data skewness. Furthermore, when heterogeneity was retrieved, a random-effect model was applied in the statistical analysis, but, at the same time, an I² metric was evaluated for the random effect to check the correction of heterogeneity. On the matter of interpreting this meta-analysis results, in which the random effect method was used in some of the statistical analyses [46], while actual differences in treatments were detected (e.g., supervision in the HPT studies), the intervention resulted judiciously comparable, as the nature of the implemented rehabilitative approaches was similar. Secondly, it was not possible to perform either a sub-analysis on different types of prostheses because the majority of the included studies did not report the type of implants and surgical approaches performed nor on different HPT and/or CPT rehabilitative approaches due to the limited level of the reporting. Moreover, as per the vast majority of the overall rehabilitation clinical studies, the included studies were not blinded either to the patients and/or the involved clinicians. It should be pointed out though, that blinding rehabilitation studies is almost unfeasible considering that patients are inevitably aware of the received treatment and tend to report their experiences to the involved researchers. Additionally, liability issues, regulatory approval, and framework in different countries, as well as ethical considerations and cybersecurity risks should also be considered when evaluating the use of HPT in the clinical practice. Finally, the lack of common and validated PT programs, and the heterogeneity of the HPT protocols interventions, included the patient’s adherence to the exercise regimen in these studies, may have influenced the pooled clinical results. This last point should be addressed properly by future clinical trials: in fact, among the analyzed studies, HPT protocols included supervised PT with adherence monitored via phone calls, periodic home-visits, or mobile software/applications, but also unsupervised PT. Due to the lack of sufficient data, a sub-analysis on these two HPT approaches was not feasible. Despite recent investigations addressed the concept of supervised versus unsupervised rehabilitation suggesting comparable results [47], several aspects remain to be investigated by future properly designed clinical studies. However, regardless of these limitations, this meta-analysis was able to provide relevant data on the overall benefit of HPT, thus endorsing the possibility to adopt, for specific patients, a home-based approach after TKA surgery.

5. Conclusions

HPT is a valuable option for the post-operative rehabilitation of patients undergoing TKA, leading results comparable to CPT. This questions the need for more complex and expensive management of these patients, considering the additional HPT benefits of healthcare costs reduction, early patient discharge from the hospital, and fewer in-person physical therapy sessions, with equal patient final satisfaction. While this review offers a comprehensive representation of numerous studies, it underlies significant heterogeneity in the reported data, thereby diminishing the overall robustness of the analysis. However, future studies are needed to confirm the study results.

The corresponding author attests that all listed authors meet the authorship criteria and that no others meeting the criteria have been omitted.