Muscle deficits persist after unilateral knee replacement and have implications for rehabilitation

Early- to Mid-Term Review of a Prospective, Multi-Center, International, Outcomes Study of an Anatomically Designed Implant with Posterior-Stabilized Bearing in Total Knee Arthroplasty

Background and Objectives: National joint registries report higher total knee arthroplasty (TKA) revision rates in posterior-stabilized (PS) systems compared to non-posterior-stabilized designs. The purpose of this study was to investigate the implant survivorship and clinical outcomes of an anatomic implant with a PS bearing. Materials and Methods: An early- to mid-term follow-up of a prospective, multi-center, non-controlled outcomes study of patients who received primary TKA between November 2014 and June 2017 was performed. A total of 800 cases using PS bearings that were implanted in 664 patients were monitored post-operatively for their implant survivorship and adverse events for up to five years. The Knee Society Knee and Function scores, patient satisfaction, the five-dimensional European Quality of Life questionnaire, and range of motion (ROM) were evaluated pre-operatively and post-operatively at six weeks, six months, one year, two years, three years, and five years. Results: The mean follow-up period was 3.7 ± 1.3 years, and the three-year implant survival rate was 99.3% (95% CI: 98.4%, 99.7%) with five revisions during the five-year follow-up. Patient satisfaction was 96.1% at six weeks and increased to 99.3% at one year. All patient-reported outcome measures significantly (p < 0.0001) increased up to the one-year follow-up and then remained stable up to the five-year follow-up. Conclusions: This study supports the excellent survivorship and patient-reported outcomes of the Persona® Knee system using cemented, fixed bearing, posterior-stabilized components with minimal complications at early- to mid-term follow-up in an international Asian population. Ongoing observations are being performed to investigate the mid- to long-term survivorship and clinical outcomes associated with this knee system.

Effects of strength training on functional ambulation following knee replacement: a systematic review, meta-analysis, and meta-regression

Strength training is recommended by the American Physical Therapy Association to improve muscle strength, mobility, and balance following knee replacement. Few studies have focused on the direct effects of strength training on functional ambulation, and potential dose-response relationships between strength training parameters and the effect remain unclear. The aim of this systematic review, meta-analysis, and meta-regression was to evaluate the effects of strength training on functional ambulation following knee replacement (KR). We also aimed to explore potential dose-response relationships between strength training parameters and performance in functional ambulation. A systematic literature search of eight online databases was performed on March 12, 2023, for randomized controlled trials evaluating the effects of strength training on functional ambulation by six-minute walk test (6MWT) or timed-up and go test (TUG) after KR. Data were pooled by random-effect meta-analyses and presented as weighted mean difference (WMD). A random-effect meta-regression was performed for four predetermined training parameters, namely, duration (weeks), frequency (sessions per week), volume (time per session), and initial time (after surgery) separately to explore dose-response relationships with WMD. Fourteen trials encompassing 956 participants were included in our study. Meta-analyses showed an improvement in 6MWT performance after strength training (WMD: 32.15, 95% CI 19.44-44.85) and a decrease in time to complete TUG (WMD: - 1.92, 95% CI - 3.43 to - 0.41). Meta-regression revealed a dose-response relationship only between volume and 6MWT, with a decreasing trend (P = 0.019, 95% CI - 1.63 to - 0.20). Increasing trends of improvement in 6MWT and TUG were observed with increasing training duration and frequency. A slight decreasing trend of improvement was observed in 6MWT with postponed initial time, while an opposite trend was observed in TUG. Based on existing studies, moderate-certainty evidence suggests that strength training could increase 6MWT distance, and low-certainty evidence shows that strength training could decrease the time to complete TUG after KR. Meta-regression results only suggested a dose-response relationship between volume and 6MWT with a decreasing trend.Registration: PROSPERO: CRD42022329006.

Retrograde Training: Effects on Lower Body Strength and Power

Backward walking and running on positive grades (retrograde training) represents a closed kinetic chain exercise used by rehabilitation specialists for patellofemoral-related injuries. To date, no longitudinal studies exist to support it use. This investigation examined the effects of retrograde training on lower body strength and power in recreational athletes aged 18-50 years over 6 weeks. Thirty-seven subjects were divided into two groups. Group 1 performed retrograde training 3 days∙wk^-1 using treadmill speeds, grades and bout durations ranging from 1.6-4.9 m∙sec^-1, 2.5-27.5% and 10-30 seconds, respectively (RG, n=19). Group 2 was a control group who continued their normal training (CON, n=18). Pre- and posttests assessed a variety of unilateral and bilateral measures including vertical and linear jumps, one repetition maximum leg press strength, and positive and negative power during weighted squat jumping on a horizontal leg press with a force plate. RG improved significantly in all tests (P<0.05). Mean effect size (ES) of the relative improvement in a majority of tests revealed a moderate to very large ES of RG training (ES range: 0.77-2.71). We conclude retrograde training effective for improving lower body strength and power in recreational athletes.

Periarticular muscle status affects in vivo tibio-femoral joint loads after total knee arthroplasty

Background: Total knee arthroplasty (TKA) is a highly effective treatment for severe knee osteoarthritis that is increasingly performed in younger, more active patients. As postoperative muscular impairments may negatively affect surgical outcomes and implant longevity, functional muscle recovery gains increasing importance in meeting future patient demands. This study aimed to assess the status of periarticular muscles in the long-term follow-up after TKA and to evaluate its impact on in vivo tibio-femoral joint loads. Methods: A case series was created, with eight patients with knee osteoarthritis. All subjects received an instrumented knee implant in unilateral TKA. Native computed tomography scans, acquired pre and postoperatively, were used to evaluate distal muscle volumes and fatty infiltration. In vivo tibio-femoral joint loads were measured telemetrically during standing, walking, stair climbing and chair rising and were correlated to muscle status. Results: Postoperatively a reduction in fatty infiltration across all periarticular muscles was pronounced. High average peak loads acted in the tibio-femoral joint ranging from 264% during stand-to-sit activities up to 341% body weight (BW) during stair descent. Fatty infiltration of the m. quadriceps femoris and hamstrings were associated with increased tibio-femoral joint contact forces during walking (r = 0.542; 0.412 and 0.766). Conclusion: The findings suggest that a fatty infiltration of periarticular muscles may lead to increased tibio-femoral joint contact forces. However, we only observed weak correlations between these parameters. Improvements in functional mobility and the restoration of a pain-free joint likely explain the observed postoperative reductions in fatty infiltration. Perioperative rehabilitation approaches targeting residual impairments in muscle quality could, contribute to reduced tibio-femoral joint loads and improved long-term outcomes of TKA. However, it has to be pointed out that the study included a small number of patients, which may limit its validity.

Effectiveness of Gamification in Knee Replacement Rehabilitation: Protocol for a Randomized Controlled Trial With a Qualitative Approach

BACKGROUND

Exergames can provide encouraging exercise options. Currently, there is limited evidence regarding home-based exergaming in the postoperative phase of total knee replacement (TKR).

OBJECTIVE

This study aimed to investigate the effects of a 4-month postoperative home-based exergame intervention with an 8-month follow-up on physical function and symptoms among older persons undergoing TKR compared with home exercise using a standard protocol. In addition, a concurrent embedded design of a mixed methods study was used by including a qualitative component within a quantitative study of exergame effects.

METHODS

This was a dual-center, nonblinded, two-arm, parallel group randomized controlled trial with an embedded qualitative approach. This study aimed to recruit 100 patients who underwent their first unilateral TKR (aged 60-75 years). Participants were randomized to the exergame or standard home exercise arms. Participants followed a custom-made exergame program independently at their homes daily for 4 months. The primary outcomes at 4 months were function and pain related to the knee using the Oxford Knee Score questionnaire and mobility using the Timed Up and Go test. Other outcomes, in addition to physical function, symptoms, and disability, were game user experience, exercise adherence, physical activity, and satisfaction with the operated knee. Assessments were performed at the preoperative baseline and at 2, 4, and 12 months postoperatively. Exergame adherence was followed from game computers and using a structured diary. Self-reported standard exercise was followed for 4 months of intervention and physical activity was followed for 12 months using a structured diary. Qualitative data on patients' perspectives on rehabilitation and exergames were collected through laddering interviews at 4 and 12 months.

RESULTS

This study was funded in 2018. Data collection began in 2019 and was completed in January 2022. The COVID-19 pandemic caused an unavoidable situation in the study for recruitment, data collection, and statistical analysis. As of November 2020, a total of 52 participants had been enrolled in the study. Primary results are expected to be published by the end of 2022.

CONCLUSIONS

Our study provides new knowledge on the effects of postoperative exergame intervention among older patients with TKR. In addition, this study provides a new understanding of gamified postoperative rehabilitation, home exercise adherence, physical function, and physical activity among older adults undergoing TKR.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03717727; https://clinicaltrials.gov/ct2/show/NCT03717727.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR1-10.2196/38434.

Exploratory insights into novel prehabilitative neuromuscular exercise-conditioning in total knee arthroplasty

BACKGROUND

Contemporary strategies for prehabilitation and rehabilitation associated with total knee arthroplasty (TKA) surgery have focused on improving joint range-of-motion and function with less emphasis on neuromuscular performance beneficially affecting joint stability. Furthermore, prehabilitation protocols have been found to be too long and generic-in-effect to be considered suitable for routine clinical practice.

METHODS

A pragmatic exploratory controlled trial was designed to investigate the efficacy of a novel, acute prehabilitative neuromuscular exercise-conditioning (APNEC) in patients electing TKA. Adults electing unilateral TKA were assessed and randomly allocated to exercise-conditioning (APNEC, n = 15) and usual care (Control, n = 14) from a specialised orthopaedic hospital, in the United Kingdom. APNEC prescribed nine stressful exercise-conditioning sessions for the knee extensors of the surgery leg, accrued over one week (3 sessions·week^-1; 36 exercise repetitions in total; machine, gravity-loaded) and directly compared with usual care (no exercise). Prescribed exercise stress ranged between 60%-100% of participant's daily voluntary strength capacity, encompassing purposefully brief muscular activations (≤ 1.5 s). Baseline and follow-up indices of neuromuscular performance focusing on muscle activation capacity (electromechanical delay [EMD], rate of force development [RFD] and peak force [PF]) were measured ipsilaterally using dynamometry and concomitant surface electromyography (m. rectus femoris_[RF] and m. vastus lateralis_[VL]).

RESULTS

Group mean ipsilateral knee extensor muscular activation capacity (EMD_RF [F_(3,57) = 53.5; p < 0.001]; EMD_VL [F_(3,57) = 50.0; p < 0.001]; RFD [F_(3,57) = 10.5; p < 0.001]) and strength (PF [F_(3,57) = 16.4; p < 0.001]) were significantly increased following APNEC (Cohen's d, 0.5-1.8; 15% to 36% vs. baseline), but unchanged following no exercise control (per protocol, group by time interaction, factorial ANOVA, with repeated measures), with significant retention of gains at 1-week follow-up (p < 0.001).

CONCLUSIONS

The exploratory APNEC protocol elicited significant and clinically-relevant improvement and its retention in neuromuscular performance in patients awaiting TKA.

TRIAL REGISTRATION

(date and number): clinicaltrial.gov: NCT03113032 (4/04/2017) and ISRCTN75779521 (3/5/2017).

Clinically Important Reductions in Physical Function and Quality of Life in Adults with Tumor Prostheses in the Hip and Knee: A Cross-sectional Study

BACKGROUND

Patients with a bone sarcoma who undergo limb-sparing surgery and reconstruction with a tumor prosthesis in the lower extremity have been shown to have reduced self-reported physical function and quality of life (QoL). To provide patients facing these operations with better expectations of future physical function and to better evaluate and improve upon postoperative interventions, data from objectively measured physical function have been suggested.

QUESTIONS/PURPOSES

We sought to explore different aspects of physical function, using the International Classification of Functioning, Disability, and Health (ICF) as a framework, by asking: (1) What are the differences between patients 2 to 12 years after a bone resection and reconstruction surgery of the hip and knee following resection of a bone sarcoma or giant cell tumor of bone and age-matched controls without walking limitations in ICF body functions (ROM, muscle strength, pain), ICF activity and participation (walking, getting up from a chair, daily tasks), and QoL? (2) Within the patient group, do ICF body functions and ICF activity and participation outcome scores correlate with QoL?

METHODS

Between 2006 and 2016, we treated 72 patients for bone sarcoma or giant cell tumor of bone resulting in bone resection and reconstruction with a tumor prosthesis of the hip or knee. At the timepoint for inclusion, 47 patients were alive. Of those, 6% (3 of 47) had undergone amputation in the lower limb and were excluded. A further 32% (14 of 44) were excluded because of being younger than 18 years of age, pregnant, having long transportation, palliative care, or declining participation, leaving 68% (30 of 44) for analysis. Thus, 30 patients and 30 controls with a mean age of 51 ± 18 years and 52 ± 17 years, respectively, were included in this cross-sectional study. Included patients had been treated with either a proximal femoral (40% [12 of 30]), distal femoral (47% [14 of 30]), or proximal tibia (13% [4 of 30]) reconstruction. The patients were assessed 2 to 12 years (mean 7 ± 3 years) after the resection-reconstruction. The controls were matched on gender and age (± 4 years) and included if they considered their walking capacity to be normal and had no pain in the lower extremity. Included outcome measures were: passive ROM of hip flexion, extension, and abduction and knee flexion and extension; isometric muscle strength of knee flexion, knee extension and hip abduction using a hand-held dynamometer; pain intensity (numeric rating scale; NRS) and distribution (pain drawing); the 6-minute walk test (6MWT); the 30-second chair-stand test (CST); the Toronto Extremity Salvage Score (TESS), and the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30). The TESS and the EORTC QLQ-C30 were normalized to 0 to 100 points. Higher scoring represents better status for TESS and EORTC global health and physical functioning scales. Minimum clinically important difference for muscle strength is 20% to 25%, NRS 2 points, 6MWT 14 to 31 meters, CST 2 repetitions, TESS 12 to 15 points, and EORTC QLQ-C30 5 to 20 points.

RESULTS

Compared with controls, the patients had less knee extension and hip abduction strength in both the surgical and nonsurgical limbs and regardless of reconstruction site. Mean knee extension strength in patients versus controls were: surgical limb 0.9 ± 0.5 Nm/kg versus 2.1 ± 0.6 Nm/kg (mean difference -1.3 Nm/kg [95% CI -1.5 to -1.0]; p < 0.001) and nonsurgical limb 1.7 ± 0.6 Nm/kg versus 2.2 ± 0.6 Nm/kg (mean difference -0.5 Nm/kg [95% CI -0.8 to -0.2]; p = 0.003). Mean hip abduction strength in patients versus controls were: surgical limb 1.1 ± 0.4 Nm/kg versus 1.9 ± 0.5 Nm/kg (mean difference -0.7 Nm/kg [95% CI -1.0 to -0.5]; p < 0.001) and nonsurgical limb 1.5 ± 0.4 Nm/kg versus 1.9 ± 0.5 Nm/kg (-0.4 Nm/kg [95% CI -0.6 to -0.2]; p = 0.001). Mean hip flexion ROM in patients with proximal femoral reconstructions was 113° ± 18° compared with controls 130° ± 11° (mean difference -17°; p = 0.006). Mean knee flexion ROM in patients with distal femoral reconstructions was 113° ± 29° compared with patients in the control group 146° ± 9° (mean difference -34°; p = 0.002). Eighty-seven percent (26 of 30) of the patients reported pain, predominantly in the knee, anterior thigh, and gluteal area. The patients showed poorer walking and chair-stand capacity and had lower TESS scores than patients in the control group. Mean 6MWT was 499 ± 100 meters versus 607 ± 68 meters (mean difference -108 meters; p < 0.001), mean CST was 12 ± 5 repetitions versus 18 ± 5 repetitions (mean difference -7 repetitions; p < 0.001), and median (interquartile range) TESS score was 78 (21) points versus 100 (10) points (p < 0.001) in patients and controls, respectively. Higher pain scores correlated to lower physical functioning of the EORTC QLQ-C30 (Rho -0.40 to -0.54; all p values < 0.05). Less muscle strength in knee extension, knee flexion, and hip abduction correlated to lower physical functioning of the EORTC QLQ-C30 (Rho 0.40 to 0.51; all p values < 0.05).

CONCLUSION

This patient group demonstrated clinically important muscle weaknesses not only in resected muscles but also in the contralateral limb. Many patients reported pain, and they showed reductions in walking and chair-stand capacity comparable to elderly people. The results are relevant for information before surgery, and assessments of objective physical function are advisable in postoperative monitoring. Prospective studies evaluating the course of physical function and which include assessments of objectively measured physical function are warranted. Studies following this patient group with repetitive measures over about 5 years could provide information about the course of physical function, enable comparisons with population norms, and lead to better-designed, targeted, and timely postoperative interventions.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Gait mechanics are influenced by quadriceps strength, age, and sex after total knee arthroplasty

Although most patients are satisfied with outcomes after total knee arthroplasty (TKA), many retain preoperative altered gait mechanics. Identifying patient characteristics associated with gait mechanics will improve rehabilitation strategies and enhance our understanding of movement disorders. Therefore, the purpose of this study was to identify which patient characteristics are related to gait mechanics in the surgical limb during walking post-TKA. Patient characteristics included age, body mass, sex, quadriceps strength, self-reported function, and knee pain. General linear regression was used to compare patient characteristics associated with gait mechanics, after controlling for gait speed, functional capacity and time from surgery. We tested 191 patients cross-sectionally at 6-24 months after primary, unilateral TKA. Quadriceps weakness in the surgical limb was associated with less peak vertical ground reaction force (PvGRF) (β = .245, p = .044), knee extension moment (β = .283, p = .049), and knee extension excursion (β = .298, p = .038). Older age (β = .168, p = .050) was associated with less PvGRF. Quadriceps strength in the nonsurgical limb (β = -.357, p = .021) was associated with greater knee extension excursion in the surgical limb. Females with TKA (β = -.276, p = .007) had less knee flexion excursion compared to males. Faster gait speed was also associated with greater PvGRF (β = .585, p < .001), knee extensor moment (β = .481, p < .001), and knee flexion excursion (β = .318, p < .001). Statement of Clinical Significance: This study showed quadriceps weakness, slower gait speed, older age and being female were related to altered gait mechanics post-TKA. These findings will help clinicians better educate patients and develop targeted interventions for improving care in patients post-TKA.

Comparison of two different models of rehabilitation programs following total knee replacement operations

Background

Total knee replacement operation (TKR) is the treatment of choice in severe knee osteoarthritis (OA). Rehabilitation post-TKR is still not well studied. The aim of this study was to compare between the high-intensity (HI) rehabilitation program and the low-intensity (LI) rehabilitation program following TKR.

Results

At 1 month following the TKR operations, significant improvements were found in the first group compared to the second group in all the measured parameters except for the knee range of motion (ROM). At 3 and 12 months follow-up periods, there were statistically significant differences between both groups in all the evaluated parameters except for the numeric pain rating scale and the knee ROM.

Conclusions

Both high-intensity and low-intensity rehabilitation programs are effective; however, HI program had superior functional gain and patient-reported outcomes compared to the LI program. Moreover, HI group has a long-term functional gain.

Improvements in Isokinetic Quadriceps and Hamstring Strength Testing After Focused Therapy in Patients With Flexion Instability

BACKGROUND

There is a paucity of literature to guide non-operative treatment for patients with problems after total knee arthroplasty (TKA). We sought to quantify how quadriceps and hamstring strength could improve with focused physical therapy (PT) and whether improving leg strength may prevent revision surgery for patients with flexion instability (FI) after TKA.

METHODS

This retrospective study included patients diagnosed with FI by one of the 4 fellowship-trained arthroplasty surgeons at a single academic institution. Patients with FI were referred for strength measurements and a focused PT program. In total, 166 patients completed isokinetic testing to quantify their relative quadriceps and hamstring power, torque, and work measures compared to their contralateral leg. Fifty-five (33.5%) patients subsequently completed post-PT isokinetic testing. Statistical analysis was conducted to evaluate strength deficits in the knee with FI.

RESULTS

Patients with FI were found to be 20.5%-38.4% weaker in all strength domains compared to the contralateral leg (P < .001). Patients who completed PT and pre-isokinetic and post-isokinetic testing demonstrated statistically significant gains in all extension metrics by a net range of 24.7%-34.2% (P = .011-.029) and their flexion strength metrics improved by 32.5%-40.2% (P = .002-.005). About 81.9% of patients in this subgroup did not undergo revision TKA. Those subjects who went on to revision did not statistically improve in any strength domain (P = .063-.121).

CONCLUSION

Patients with FI after TKA have significantly weaker quadriceps and hamstrings in the operative compared to contralateral leg. Patients who did not undergo revision knee arthroplasty and completed a formal PT program improved quadriceps and hamstring strength by 30%.

LEVEL OF EVIDENCE

IV (Case series).

Electrical Stimulation of Muscle: Electrophysiology and Rehabilitation

The generation of action potentials in intramuscular motor and sensory axons in response to an imposed external current source can evoke muscle contractions and elicit widespread responses throughout the nervous system that impact sensorimotor function. The benefits experienced by individuals exposed to several weeks of treatment with electrical stimulation of muscle suggest that the underlying adaptations involve several physiological systems, but little is known about the specific changes elicited by such interventions.

Effectiveness of ultrasonographic skeletal muscle assessment in patients after total knee arthroplasty

Objectives

This study aimed to characterize the skeletal muscles of patients who underwent total knee arthroplasty (TKA) using ultrasonography in order to investigate the effectiveness of ultrasonographic skeletal muscle assessment after TKA.

Methods

This study included 50 TKA patients (TKA group) and 41 residents with osteoarthritis who have not received TKA (non-TKA group). Ultrasonography was used to assess the characteristics of several different muscles. Various postoperative outcomes were evaluated. Muscle thickness (MT) and echo intensity (EI) results were compared among operated knees in the TKA group, nonoperated knees in the TKA group, and more severely affected knees in the non-TKA group. For the TKA group, multiple regression was conducted to examine the association between skeletal muscle characteristics of operated knees and postoperative outcomes.

Results

The MTs of the vastus medialis, vastus intermedius, and rectus femoris (RF) were significantly smaller and the RF-EI was significantly greater for both operated and nonoperated knees in the TKA group compared with the non-TKA group (P < 0.017). Several parameters of physical function were significantly poorer in the TKA group than in the non-TKA group (P < 0.05). Multiple regression demonstrated that RF-MT was associated with knee range of motion, knee strength, and physical functional performance in the TKA group (P < 0.05).

Conclusions

The quantity and quality of skeletal muscles were lower in the TKA group than in the non-TKA group. Ultrasonography may be useful for assessing skeletal muscles in TKA patients because MT assessed with ultrasonography was associated with various parameters of physical function.

Early initiation of home-based sensori-motor training improves muscle strength, activation and size in patients after knee replacement: a secondary analysis of a controlled clinical trial

Background

There is accumulating evidence for the advantages of rehabilitation involving sensori-motor training (SMT) following total knee replacement (TKR). However, the best way in which to deliver SMT remains elusive because of potential interference effects amongst concurrent exercise stimuli for optimal neuromuscular and morphological adaptations. The aim of this study was to use additional outcomes (i.e. muscle strength, activation and size) from a published parent study to compare the effects of early-initiated home-based rehabilitative SMT with functional exercise training (usual care) in patients undergoing TKR.

Methods

A controlled clinical trial was conducted at the Orthopedic University Hospital of Rion, Greece involving allocation concealment to patients. Fifty-two patients electing to undergo TKR were randomised to either early-initiated SMT [experimental] or functional exercise training [control] in a home-based environment. Groups were prescribed equivalent duration of exercise during 12-weeks, 3–5 sessions of ~ 40 min per week of home-based programmes. Muscle strength and activation (peak force [PF]; peak amplitude [Peak Amp.] and root mean square of integrated electromyography [RMS iEMG]), muscular size (including rectus femoris muscle cross-sectional area [CSA_RF]), and knee ROM were assessed on three separate occasions (pre-surgery [0 weeks]; 8 weeks post-surgery; 14 weeks post-surgery).

Results

Patients undertaking SMT rehabilitation showed significantly greater improvements over the 14 weeks compared to control in outcomes including quadriceps PF (25.1 ± 18.5 N vs 12.4 ± 20.8 N); iPeak Amp. (188 ± 109.5% vs 25 ± 105.8%); CSA_RF (252.0 ± 101.0 mm² vs 156.7 ± 76.2 mm²), respectively (p < 0.005); Knee ROM did not offer clinically relevant changes (p: ns) between groups over time. At 14 weeks post-surgery, the SMT group’s and control group’s performances differed by relative effect sizes (Cohen’s d) ranging between 0.64 and 1.06.

Conclusion

A prescribed equivalent time spent in SMT compared to usual practice, delivered within a home-based environment, elicited superior restoration of muscle strength, activation and size in patients following TKR.

Trial registration

ISRCTN12101643, December 2017 (retrospective registration).

Electronic supplementary material

The online version of this article (10.1186/s12891-019-2575-3) contains supplementary material, which is available to authorized users.

Relationship Between Strength Parameters and Functional Performance Tests in Patients With Severe Knee Osteoarthritis

BACKGROUND

Decreased leg muscle strength is a major determinant of reduced function in patients with knee osteoarthritis (OA). The identification of a strength parameter that is best correlated with functional performance is important for monitoring rehabilitation results.

OBJECTIVE

To determine which muscle strength measurements show the highest correlation with functional capacity in patients with severe knee OA shortly before total knee arthroplasty (TKA).

DESIGN

Cross-sectional exploratory study.

SETTING

Outpatient rehabilitation department at a university teaching hospital.

PATIENTS

The sample included 75 patients (51 female) scheduled for primary TKA, recruited through multistage sampling.

METHODS OR INTERVENTIONS

Independent variables were peak isometric, isokinetic concentric, and eccentric leg extensor strength measured on the leg press, as well as peak isometric knee extensor strength measured on the strength chair. Two multiple regression analyses were performed, one including all strength measures and the other including all of the strength ratios. Pearson correlation coefficients were calculated between the strength measures and functional test scores.

MAIN OUTCOME MEASUREMENTS

Dependent variables were the Timed Up and Go Test (TUG) and the Stair Test (ST).

RESULTS

The regression analysis including all strength measures could explain 11.9% of the variance of the TUG (P = .068, not significant [NS]) and 21.5% of the variance of the ST (P = .009, significant). The regression model for the strength ratios explained 11.8% of the variance of the TUG (P = .090, NS) and 6.3% of the ST (P = .217, NS).

CONCLUSIONS

Although univariate analysis confirmed significant correlations between strength measurements and functional tests, multiple regression analysis revealed a higher predictive value for the ST than for the TUG. The use of both muscle strength tests and performance-based function tests is advisable to evaluate functional impairments of patients with knee OA.

LEVEL OF EVIDENCE

III.

Effects of Elastic Band Exercise on Lower Limb Rehabilitation of Elderly Patients Undergoing Total Knee Arthroplasty

PURPOSE

The aim of the study was to investigate the effect of elastic band exercise activities on lower extremity rehabilitation in elderly patients subjected to an elastic band exercise intervention 2 and 4 weeks after total knee arthroplasty.

DESIGN

A quasiexperimental study was conducted. Participants were recruited from southern Taiwan who were over 65 years old and had a first unilateral total knee arthroplasty for osteoarthritis.

METHODS

The control and experimental groups comprised 25 patients each. The control group received conventional treatment after total knee arthroplasty; by contrast, the experimental group engaged in elastic band exercise activities demonstrated by instructors, in addition to receiving conventional treatment. Effects of the lower extremity rehabilitation of the two groups were evaluated 2 and 4 weeks after total knee arthroplasty.

FINDINGS

Most of the participants were above 70 years of age, 17 of whom were in the control group (68%) and 16 in the experimental group (64%). The active and passive knee flexion angles of the experimental group were greater than those of the control group (p < .001) 2 and 4 weeks after surgery. The muscle strength of the quadriceps of the experimental group was higher than that of the control group (p < .001) 2 and 4 weeks after surgery. The experimental group exhibited significantly higher physical function than that of the control group 2 and 4 weeks after surgery (p < .001).

CONCLUSIONS

The elastic band exercise program shows promising effects on improving the lower limb rehabilitation of elderly patients with total knee arthroplasty.

CLINICAL RELEVANCE

Healthcare professionals who work with elderly patients with total knee arthroplasty may consider recommending and implementing the elastic band exercise program as a home rehabilitation method for this population. However, we recommend further testing of the long-term effects of this program on a larger population.

The Positive Benefits of Negative Movement Patterns Following Total Knee Arthroplasty

Introduction:

Eccentric (negative) resistance exercise of the legs using specialized machines has been reported to be useful and often superior to standard exercise following total knee arthroplasty (TKA). Movements that utilize body mass and gravity as a mode of eccentric resistance exercise in a more pragmatic rehabilitation paradigm may also be useful in reversing chronic muscle impairments observed years following surgery. This study explores whether an eccentrically biased, body mass resistance exercise induces greater magnitude of sagittal plane extensor angular impulse of the support torque and individual net joint torque contributions during both squatting and lunging movement patterns 6 weeks following TKA.

Methods:

Cross-sectional laboratory-based study design including 10 patients following primary unilateral TKA (6.5 ± 0.8 weeks.). All patients completed 3 trials of the squat and lunge movement pattern under both a concentric and an eccentric condition. Extensor angular impulse of the support torque and net joint torque contributions were calculated by integrating the joint torque versus time curves. A Two-way analysis of covariance was conducted and contracts of clinical interest were computed using Wald posttest. P Values for all pairwise comparisons were adjusted for multiplicity using Bonferroni multiple comparison procedure.

Results:

The eccentric condition, compared to the concentric condition, displayed larger magnitude of extensor angular impulse during both the squat (P < .001) and lunge (P < .001) movement patterns for the support torques. Similarly, the eccentric condition, compared to the concentric condition, displayed larger magnitude of extensor angular impulse of the hip, knee, and ankle (P < .001) during both movement patterns.

Conclusion:

Eccentrically biased, body mass movement exercises can produce higher levels of extensor angular impulse on the surgical limb in patients early after TKA. Patients in this study were able to tolerate the higher extensor angular impulse demands and performed the eccentrically biased conditions (without specialized machines) that could be beneficial in postoperative rehabilitation.

High-Velocity Quadriceps Exercises Compared to Slow-Velocity Quadriceps Exercises Following Total Knee Arthroplasty: A Randomized Clinical Study

BACKGROUND AND PURPOSE

Despite improvement in pain and perceived function in older adults following total knee arthroplasty (TKA), objective outcome measures of muscular impairment and ambulatory function demonstrate significant deficits. Evidence suggests that quadriceps power may play a greater role in ambulatory function than measures of strength alone following TKA. The purpose of this study was to compare the effect of high-velocity (HV) quadriceps exercises with that of slow-velocity (SV) quadriceps exercises on functional outcomes and quadriceps power following TKA.

METHODS

This study was a randomized clinical study conducted in an outpatient physical therapy clinic. Twenty-one participants who were 4 to 6 weeks post unilateral TKA were randomly assigned to an HV or SV group. Participants performed an evidence-based standardized progressive resistance exercise program in addition to HV quadriceps exercises or SV quadriceps exercises. Participants attended 2 sessions per week for 8 weeks. Before and after the 8-week exercise intervention, participants completed a functional questionnaire, health survey, functional testing, and underwent quadriceps strength and power testing.

RESULTS

Both groups demonstrated improvements in ambulatory outcome measures, strength, speed, and power. The HV group demonstrated significantly greater improvements in distance walked and quadriceps strength than the SV group.

LIMITATIONS

These data should be considered preliminary because of a small sample size.

CONCLUSION

HV quadriceps exercises may be an effective rehabilitation strategy in conjunction with a standardized progressive resistance exercise program beginning 4 to 6 weeks after TKA.

Joint mechanical asymmetries during low- and high-demand mobility tasks: Comparison between total knee arthroplasty and healthy-matched peers

Chronic inter-limb joint mechanical asymmetry has been reported following total knee arthroplasty (TKA) during low-demand mobility tasks such as level walking. However, no study has compared the inter-limb asymmetry during a high-demand mobility task such as decline walking. The objective of this cross-sectional study was to compare inter-limb asymmetry differences during both level and decline walking tasks at six months following TKA compared to asymmetry present in an age, gender, body mass index and activity level matched healthy cohort. Kinetic and kinematic gait analysis was conducted on 42 patients with TKA and 15 healthy-matched peers. Our inter-limb asymmetry results demonstrated significantly (p<0.05) greater combined limb support moment (M_S) (mean differences [MD]=0.17; 95% CI=0.07, 0.22), knee extensor moment (M_K) (MD=0.05; 95% CI=0.02, 0.09) and vertical ground reaction force (vGRF) (MD=0.03; 95% CI=0.01, 0.08) differences during decline walking compared to level walking in patients with TKA. Greater M_S (MD=0.24; 95% CI=0.13, 0.35), M_K (MD=0.08; 95% CI=0.03, 0.18), vGRF (MD=0.04; 95% CI=0.01, 0.08) and knee joint angle (MD=2.4; 95% CI=0.37, 3.80) differences were present in patients with TKA compared to healthy-matched peers during decline walking. Greater M_S (MD=0.13; 95% CI=0.05, 0.20) and plantarflexor moment (MD=0.06; 95% CI=0.04, 0.16) differences were present in patients with TKA compared to healthy-matched peers during level walking. Post-TKA inter-limb asymmetry during level walking worsens as the physical demands of the task are increased. Thus, even patients with good self-reported outcomes after TKA exhibit substantial deficits in their mobility reserves that could limit their independence and community mobility as they age.

The effect of primary total knee arthroplasty on the incidence of falls and balance-related functions in patients with osteoarthritis

Knee osteoarthritis (OA) is an established risk factor for falls and balance impairment. This study investigated the incidence of falls, balance-related outcomes and risk factors for falls before and after primary total knee arthroplasty (TKA). Three hundred seventy-six OA patients scheduled to undergo TKA were included. Falls data within the preoperative, first postoperative and second postoperative years were collected, balance-related functions were assessed using the Assessment of Quality of Life (AQoL), WOMAC, Falls Efficacy Scale International (FES-I), Activities-specific Balance Confidence (ABC), knee extension strength, Berg Balance Scale (BBS) and Timed Up and Go (TUG) before surgery and 1 and 2 years after surgery. Compared with preoperative values, the incidence of falls significantly decreased (14.89%, 6.23% and 3.14% within the preoperative, first postoperative and second postoperative years, respectively) and the AQoL, WOMAC, FES-I, ABC, knee extension strength, BBS and TUG significantly improved after TKA. Logistic regression analysis revealed that Kellgren-Lawrence grade ≥ 3 of the contralateral knee was an independent risk factor for falls before and after TKA. Conclusively, primary TKA is associated with a reduced incidence of falls and improved balance-related functions, and the contralateral knee should be considered in the design of fall-prevention strategies in patients with OA.

Effects of an over-ground exoskeleton on external knee moments during stance phase of gait in healthy adults

BACKGROUND

Physical activity and exercise is central to conservative management of knee osteoarthritis (KOA), but is often difficult for patients with KOA to maintain over the decade or more prior to surgical management. Better approaches are needed for maintaining physical function and health in this population that can also address the patho-biomechanics of the osteoarthritic knee. The objective of the study is to quantify how a lower-extremity robotic exoskeleton (dermoskeleton) modifies the external knee moments during over-ground walking in a sample of healthy adults, and to evaluate these biomechanical modifications in the context of the osteoarthritic knee.

METHOD

Motion analysis data was acquired for 13 participants walking with and without the dermoskeleton. Force plate data, external knee moment arms, and knee moments in the laboratory and tibia frames of reference were computed, as well as time-distance parameters of walking, and compared between the two conditions.

RESULTS

Although gait speed was not different, users took shorter and wider steps when walking with the dermoskeleton. Ground reaction forces and early-stance knee moment increased due to the added mass of the dermoskeleton, but the knee adduction moment was significantly reduced in late stance phase of gait. There was no effect on the knee torsional moment when measured in the anatomical frame of reference, and the late-stance knee flexion moment was invariant.

CONCLUSIONS

The dermoskeleton demonstrated favorable biomechanical modifications at the knee in healthy adults while walking. Studies are warranted to explore this technology for enabling physical activity-based interventions in patients with KOA.

Preoperative factors related to the ambulatory status at 1 year after total knee arthroplasty

PURPOSE

The purpose of this study is to investigate whether preoperative factors can predict the ambulatory status at 1 year after primary total knee arthroplasty (TKA).

METHODS

The subjects were 115 patients who had undergone TKA. Isometric lower limb muscle strength was measured and the Timed Up and Go (TUG) test and the 2011 knee society scoring were conducted preoperatively. Then, the patients were divided into two groups after surgery: a cane-assisted walking group (n = 42) and independent walking group (n = 73). Unpaired t-test, chi-square test, Mann-Whitney U-test, logistic regression analysis and the receiver-operating characteristic curve analysis were used in this study.

RESULTS

A multiple logistic regression analysis selected age, TUG test and functional activities as significant variables estimating the use of a cane after surgery. Receiver-operating characteristic curve analyses revealed that the cut-off score for TUG test was 10.8 s (sensitivity = 69%, specificity = 67%, area under curve = 0.81) and the cut-off score for functional activities was 39 points (sensitivity = 83%, specificity = 63%, area under curve = 0.83) in predicting the ambulatory status.

CONCLUSIONS

Preoperative TUG test with a cut-off score of 10.8 s and functional activities with a cut-off score of 39 points are reliable assessment tools for predicting the use of walking aid following TKA. Implications for Rehabilitation An accurate prediction of the ambulatory status after total knee arthroplasty can aid patients in understanding their own goals of the activities of daily living. Preoperative timed up and go test of <10.8 s and a preoperative functional activities functional activities score in the 2011 knee society scoring >39 points are useful for predicting the ambulatory status after total knee arthroplasty.

Effect of total knee replacement surgery and postoperative 12 month home exercise program on gait parameters

OBJECTIVE

To evaluate the effects of surgery and a postoperative progressive home exercise program on gait parameters among individuals operated with total knee arthroplasty.

DESIGN

Single blinded randomized controlled trial.

SUBJECTS

108 patients (84 females, 24 males, mean age 69 years).

INTERVENTIONS

Patients were equally randomized into an exercise group (EG) and control group (CG). The 12-months progressive home exercise program starting two months postoperatively was compared to usual care.

METHODS

Gait analysis was performed using the Gaitrite electronic walkway system. In addition, knee extension and flexion strength were measured by a dynamometer preoperatively, and pain on visual analog scale (VAS) at two months and 14 months postoperatively.

RESULTS

At the 12-month follow-up, maximal gait velocity (p=0.006), cadence (p=0.003) and stance time (p=0.039) showed a greater increase among EG than CG. All the other gait parameters improved among both groups, but with not statistically discernible difference between groups. Weak correlations were found between changes in maximal gait velocity and the knee extension (r=-0.31, p=0.002), flexion strength (r=0.28, p=0.004) and pain during loading (r=-0.27, p=0.005) values.

CONCLUSION

The intervention produced statistically significant changes in maximal gait velocity, cadence and stance times in the exercise group compared to controls. Although the average change was small it is of importance that biggest changes occurred in those with low performance.

The effect of total knee arthroplasty on patients' balance and incidence of falls: a systematic review

PURPOSE

Despite the high incidence of falls in patients with OA, few studies have explored whether falls risk is affected after patients undergo total knee arthroplasty (TKA). Therefore, the aim of this systematic review was to identify the extent of the effects of TKA on balance and incidence of falls by critically reviewing the available literature.

METHODS

A systematic review of published literature sources was conducted up to March 2014. All studies assessing balance and incidence of falls after TKA (without physiotherapeutic intervention) were included. The methodological quality of each study was reviewed using the Critical Appraisal Skill Programme tool.

RESULTS

Thirteen studies were included, comprising of ten cohort studies (Level II) and three studies with Level of evidence III.

CONCLUSIONS

Findings provide evidence that TKA improves significantly single-limb standing balance (~60%) and dynamic balance up to 1-year following surgery (Level of evidence II). Moreover, TKA influences positively fear of falling and incidence of falls by switching 54.2 % of pre-operative fallers to post-operative non-fallers (Level of evidence II-III). It is highlighted that knee extension strength, proprioception and symmetrization of postural strategies have not fully recovered post-TKA and influence balance performance. Clinically, these persistent deficits need to be mitigated by physiotherapy even before TKA takes place.

Quadriceps strength asymmetry predicts loading asymmetry during sit-to-stand task in patients with unilateral total knee arthroplasty

PURPOSE

This study aimed to examine interlimb differences in muscle strength and sit-to-stand (STS) kinetics in persons who underwent unilateral total knee arthroplasty (TKA) and to determine whether knee pain, quadriceps or hip abductor weakness contributes to altered STS performance. It was hypothesized that the operated limb would have weaker muscles, lower mechanical loading and that operated knee pain and muscle strength symmetry would predict loading symmetry between limbs during STS.

METHODS

One hundred and forty-two patients, 6 or 12 months post-unilateral TKA, underwent 3D motion analysis (VICON) of the STS task and isometric strength testing of the quadriceps and hip abductors. Knee pain was also quantified using a question from the Knee Outcome Survey-Activities of Daily Living Scale.

RESULTS

The operated limb had weaker quadriceps (P < 0.001), lower hip (P = 0.004) and knee extension moments (P < 0.001), and lower vertical ground reaction forces (P < 0.001). Operated knee pain and quadriceps strength symmetry were related to symmetry in knee extension moment (P < 0.04), and vertical ground reaction forces (P < 0.02) 6 months after surgery, while quadriceps strength symmetry was related to symmetry in vertical ground reaction forces (P = 0.03), 1 year after surgery.

CONCLUSION

Patients with unilateral TKA unload the operated limb and shift the mechanical load to the joints of the contralateral limb even 1 year after surgery. Knee pain and quadriceps strength asymmetry may play a role in the asymmetrical loading during STS post-TKA. Clinicians should consider addressing these modifiable impairments to resolve the loading asymmetry.

LEVEL OF EVIDENCE

III.

Preoperative gluteus medius muscle atrophy as a predictor of walking ability after total hip arthroplasty

PURPOSE

To elucidate the relation between certain preoperative physical parameters and walking with a limp after total hip arthroplasty (THA) and determine whether it is possible to predict the walking ability of patients 6 months after THA.

METHODS

The subjects of this study comprised 74 female patients who had undergone unilateral THA. Before surgery, the hip abductor and knee extensor strengths were measured, the cross-sectional areas (CSAs) of the gluteus medius and rectus abdominis muscles were measured, and the Timed Up and Go test was conducted. The patients were then divided into two groups according to gait observation results 6 months postoperatively: walking without a limp (n=37) and walking with a limp (n=37).

RESULTS

The discriminating criteria between the two groups were age (61 years), CSA of the gluteus medius muscle (2000 mm2), and CSA of the rectus abdominis muscle (340 mm2). In the multiple logistic regression analysis, the gluteus medius muscle was the only significant predictor of limping after THA (β=1.64, R2=0.19, p<0.01).

CONCLUSIONS

The results of the present study suggest that preoperative atrophy of the gluteus medius is an useful indicator for predicting walking with a limp 6 months postoperatively.

The efficacy of early initiated, supervised, progressive resistance training compared to unsupervised, home-based exercise after unicompartmental knee arthroplasty: a single-blinded randomized controlled trial

Objective:

To examine if supervised progressive resistance training was superior to home-based exercise in rehabilitation after unicompartmental knee arthroplasty.

Design:

Single blinded, randomized clinical trial.

Setting:

Surgery, progressive resistance training and testing was carried out at Aarhus University Hospital and home-based exercise was carried out in the home of the patient.

Subjects:

Fifty five patients were randomized to either progressive resistance training or home-based exercise.

Intervention:

Patients were randomized to either progressive resistance training (home based exercise five days/week and progressive resistance training two days/week) or control group (home based exercise seven days/week).

Main measures:

Preoperative assessment, 10-week (primary endpoint) and one-year follow-up were performed for leg extension power, spatiotemporal gait parameters and knee injury and osteoarthritis outcome score (KOOS).

Results:

Forty patients (73%) completed 1-year follow-up. Patients in the progressive resistance training group participated in average 11 of 16 training sessions. Leg extension power increased from baseline to 10-week follow-up in progressive resistance training group (progressive resistance training: 0.28 W/kg, P= 0.01, control group: 0.01 W/kg, P=0.93) with no between-group difference. Walking speed and KOOS scores increased from baseline to 10-week follow-up in both groups with no between-group difference (six minutes walk test P=0.63, KOOS P>0.29).

Conclusions:

Progressive resistance training two days/week combined with home based exercise five days/week was not superior to home based exercise seven days/week in improving leg extension power of the operated leg.

Greek Physiotherapists' Perspectives on Rehabilitation Following Total Knee Replacement: a Descriptive Survey

BACKGROUND AND PURPOSE

In Greece, as in many countries, there is a scarcity of evidence in the type of physiotherapy services offered for the rehabilitation of total knee replacement (TKR). Despite the number of TKRs annually performed in Greece (over 10,000), there are no available clinical guidelines as to the content of best physiotherapy practice. The aim of this nationwide survey undertaken by physiotherapists treating TKR patients post-operatively was to record standard practice and services available in Greece.

METHODS

Design: cross-country survey Ten per cent of all registered physiotherapists working in public/private sectors were recruited. The developed survey comprised of questions regarding therapists' profile, protocols implemented at different stages of rehabilitation and the aims and modalities used.

RESULTS

A 58.7% response rate was achieved, where 36% (47/132) of respondents were treating patients in the inpatient phase and 64% (85/132) after hospital discharge. Patients in Greece are discharged with a home-based exercise program (56.7%) and, to a lesser extent, are referred to rehabilitation centres (13.3%). Strengthening, range of movement and functionality seemed to be the primary goals especially in the inpatient phase, whereas in the outpatient phase, apart from the larger differences identified, functionality and balance training were more frequently reported.

CONCLUSIONS

No significant variations in practice were found during inpatient rehabilitation, whilst there seemed to be diversity across outpatient physiotherapy programs. The current survey suggests that patient's general health and psychological and behavioural issues are the criteria by which physiotherapists select the volume of implemented exercise and progression. However, no specific guidelines were followed. Copyright © 2016 John Wiley & Sons, Ltd.

Serial Changes of Quadriceps and Hamstring Muscle Strength Following Total Knee Arthroplasty: A Meta-Analysis

This meta-analysis was performed to analyze serial changes in thigh muscles, including quadriceps and hamstring muscles, from before to one year after total knee arthroplasty (TKA). All studies sequentially comparing isokinetic quadriceps and hamstring muscle strengths between the TKA side and the contralateral uninjured limb were included in this meta-analysis. Five studies with 7 cohorts were included in this meta-analysis. The mean differences in the strengths of quadriceps and hamstring muscles between the TKA and uninjured sides were greatest three months after surgery (26.8 N∙m, 12.8 N∙m, P<0.001), but were similar to preoperative level at six months (18.4 N∙m, 7.4 N∙m P<0.001) and were maintained for up to one year (15.9 N∙m, 4.1 N∙m P<0.001). The pooled mean differences in changes in quadriceps and hamstring strengths relative to preoperative levels were 9.2 N∙m and 4.9 N∙m, respectively, three months postoperatively (P = 0.041), but were no longer significant after six months and one year. During the year after TKA, quadriceps and hamstring muscle strengths were lowest after 3 months, recovering to preoperative level after six months, but not reaching the muscle strength on the contralateral side. Relative to preoperative levels, the difference in muscle strength between the TKA and contralateral knees was only significant at three months. Because decrease of strength of the quadriceps was significantly greater than decrease in hamstring muscle strength at postoperative three months, early rehabilitation after TKA should focus on recovery of quadriceps muscle strength.

Asymmetry in leg extension power impacts physical function in community-dwelling older women

OBJECTIVE

The aim of this study was to examine the association between asymmetry in leg extension power (LP) and lower-extremity physical function (LEF) in community-dwelling older women.

METHODS

Older women (n = 94, 74.0 ± 5.5 y) were assessed for unilateral LP (watts) using the Nottingham power rig, and absolute and relative (%ASYM) differences in LP between the dominant and nondominant legs were calculated. LEF was assessed via the 6-minute walk, 8-foot up-and-go and 30-second chair stand, and a composite measure of LEF was calculated by summing z scores of each test. In addition, body composition was measured via dual-energy x-ray absorptiometry and moderate-intensity physical activity was assessed via questionnaire.

RESULTS

The absolute difference in LP between the dominant and nondominant legs was 10.2 ± 9.0 watts, which translated to a %ASYM of 11.3% ± 10.5% (P < 0.01). %ASYM had bivariate associations with all individual measures of LEF (r range = -0.22 to -0.34, all P < 0.05). Using multivariate linear regression, %ASYM was an independent predictor of a composite LEF z score (standardized β= -0.18, P < 0.05) after adjustment for age, comorbidities, physical activity, relative adiposity, and total leg power. Analysis of covariance indicated that women with low asymmetry had a significantly better LEF z score than those with high asymmetry (0.60 vs -0.13, P = 0.04).

CONCLUSIONS

These findings indicate that a greater magnitude of asymmetry in LP is associated with poorer LEF in older women. Research is needed to determine whether interventions that correct asymmetries in lower-body muscle power confer functional benefits in older women.

Moderate varus/valgus malalignment after total knee arthroplasty has little effect on knee function or muscle strength

BACKGROUND AND PURPOSE

Postoperative muscle strength and component alignment are important factors affecting functional results after total knee arthroplasty (TKA). We are not aware of any studies that have investigated the relationship between them. We therefore investigated whether coronal malalignment of the mechanical axis and/or of individual implant components would affect knee muscle strength and function 1 year after TKA surgery.

PATIENTS AND METHODS

We included 120 consecutive osteoarthritis (OA) patients admitted for TKA. Preoperative active range of motion (ROM) of the knee, patient age, sex, and BMI were recorded and the Knee Society score (KSS) and knee joint extensor/flexor muscle strength were assessed. At 1-year follow-up, the mechanical and coronal component alignment was measured from a postoperative long standing radiograph, and ROM, KSS, and muscle strength measurements were taken in 91 patients. Functional outcome and muscle strength measurements were compared between normally aligned and malaligned TKA groups.

RESULTS

29 of 91 TKAs were malaligned, i.e. they deviated more than 3° from the neutral mechanical axis. 18 femoral components and 15 tibial components were malaligned. Before surgery, the malaligned and normally aligned groups were similar regarding sex distribution, BMI, ROM, KSS, and muscle strength. At the 1-year follow-up, the differences between the groups regarding knee joint function and muscle strength were small, not statistically significant, and barely clinically relevant.

INTERPRETATION

Moderate varus/valgus malalignment of the mechanical axis or of individual components has no relevant clinical effect on function or muscle strength 1 year after TKA surgery.

Alpine Skiing With total knee ArthroPlasty (ASWAP): effect on tendon properties

The aim of this study was to investigate the effect of alpine skiing on patellar tendon properties in patients with total knee arthroplasty (TKA). Thirty-one adults (70.4 ± 4.7 years) with unilateral TKA were recruited 2.7 ± 0.9 years after surgery and assigned to an intervention (IG) or a control group (CG). The IG underwent a 12-week guided skiing program. Tendon stiffness, Young's modulus, and cross-sectional area (CSA) were measured before and after the intervention. In both groups, mean tendon CSA was 28% (P < 0.001) larger in the operated (OP) than in the non-operated (NOP) leg at baseline, without any difference in other tendon properties. After training, stiffness increased in the IG by 5.8% and 15.8%, respectively, in the OP and NOP legs. Likewise, mean CSA increased in the IG by 2.9% in the OP and 3.8% in the NOP leg, whereas no significant changes were found for the Young's modulus. None of the tendon parameters changed in the CG. Results indicate that patellar tendon structure and/or loading pattern are altered following TKA, but this tissue seems to retain its adaptation capacity. Further, alpine skiing appears to offer a suitable rehabilitation strategy for TKA patients.

Long-term data of gait characteristics and moment-knee angle relations in female total knee arthroplasty patients

BACKGROUND

Despite the clinical success of total knee arthroplasty, impaired gait patterns and quadriceps and hamstring maximal voluntary force production might persist years post-surgery. Long-term data of gait patterns and quadriceps and hamstring maximal force production are rarely published with total knee arthroplasty patients. This work examined gait characteristics and the moment-knee angle relations of the knee extensors and flexors about 10 years post-total knee arthroplasty.

METHODS

About a decade post-surgery, 10 female total knee arthroplasty patients (64 years, mobile-bearing inlay) and 10 age-matched female controls were examined. Sagittal plane kinematics in the hip and knee joint during treadmill walking at 2 kilometres per hour were recorded using motion analysis. Spatiotemporal gait parameters were analyzed at self-selected walking speeds with a pressure-platform. The unilateral isometric moment-knee angle relations of the knee extensors and flexors and the electromyographic knee angle relation of the quadriceps were studied using dynamometry. Due to group differences for body mass index values, univariate analysis of variance (main effect: group, secondary effect: body mass index) was used for statistical analysis.

FINDINGS

Total knee arthroplasty patients demonstrated significant (P<0.05) gait deficits during constant and self-selected walking speeds and lower average absolute values in the moment-knee angle relations of the knee extensors and flexors. Significant (P<0.05) lower body-mass-normalized knee extension moments were detected at all knee joint positions for the patients.

INTERPRETATION

Long-term impairments of gait characteristics and maximal voluntary force production, especially for the knee extensors, might persist after total knee arthroplasty.

Case Report—Physical Therapy After Total Knee Replacement Surgery

The primary purpose of rehabilitation is to return the patient to a level of function enabling them to resume activities that are important to them. Physical therapy following total knee replacement has been shown to improve functional outcomes and mobility in these patients. Strength, range of motion and balance are three key components of functional rehabilitation following total knee replacement. The purpose of this report is to describe interventions following knee replacement surgery and compare them with the existing evidence. This report will focus on the outcome of two patients who underwent total knee replacement. Objective outcome measurements were then extrapolated into the “Lower Extremity Functional Scale” to better quantify and qualify functional outcome. Rehabilitation outcomes after total knee replacement surgery have been reported to include knee strength, range of motion, activities of daily living (ADLs), walking and quality of life. Both study patients participated actively with their clinical program as well as modified home programs. This report focused on three patient outcome measures; range of motion, strength and balance. Both patients had favorable outcomes that put them at a functional levels to resume their activities of daily living . The first patient had an earlier and more favorable result compared to the second patient’s outcome. Evidence supports the use of an intense progressive physical therapy program following knee replacement surgery.

Knee extensor and flexor muscle power explains stair ascension time in patients with unilateral late-stage knee osteoarthritis: a cross-sectional study

OBJECTIVES

To determine the extent of asymmetrical deficits in knee extensor and flexor muscles, and to examine whether asymmetrical muscle deficits are associated with mobility limitations in persons with late-stage knee osteoarthritis (OA).

DESIGN

Cross-sectional.

SETTING

Research laboratory.

PARTICIPANTS

A clinical sample (N=56; age range, 50-75y) of eligible persons with late-stage knee OA awaiting knee replacement.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Knee extensor and flexor power and torque assessed isokinetically; thigh muscle cross-sectional area (CSA) assessed by computed tomography; mobility limitation assessed by walking speed and stair ascension time; and pain assessed with the Western Ontario and McMaster Universities Osteoarthritis Index questionnaire.

RESULTS

The asymmetrical deficits in knee extensor and flexor power and torque were between 18% and 29% (P<.001). Regarding the thigh muscle CSA, the asymmetrical deficit was 4% (P<.001). Larger asymmetrical knee extensor power deficits and weaker knee extensor and flexor power on the contralateral side were associated with slower stair ascension times. Moreover, weaker knee extensor and flexor power on the ipsilateral side were associated with slower stair ascension times. Greater knee pain in the OA joint was independently associated with slower stair ascending time in both models.

CONCLUSIONS

The knee extensor and flexor muscle power of both the ipsilateral and contralateral sides and the pain in the OA knee were independently associated with stair ascension times. These results highlight the importance of assessing muscle power on both sides and knee pain in the prevention of mobility limitations in patients with knee OA.

Is bicompartmental knee arthroplasty more favourable to knee muscle strength and physical performance compared to total knee arthroplasty?

PURPOSE

Bicompartmental knee arthroplasty features bone and ligament sparing as unicompartmental knee arthroplasty and is presumably better in the recovery of muscle strength and function compared to total knee arthroplasty (TKA) though not previously reported in the literature. The aim of the study was to compare isokinetic knee muscle strength and physical performance in patients who underwent either bicompartmental knee arthroplasty or TKA.

METHODS

Each of 24 patients (31 knees) was prospectively examined preoperatively, at 6 and 12 months after each surgery. Isokinetic knee extensor and flexor strength as well as position sense were measured using the Biodex system. Timed up and go test, stair climbing test, and the 6-min walk test were used to assess physical performance. The results of each group were also compared with those from the corresponding healthy control, respectively.

RESULTS

Demography showed significant difference in the mean age between bicompartment (54.8 ± 5.6 years) and TKA groups (65.7 ± 6.7 years). Comparing between the two groups, knee extensor and flexor torque, hamstring/Quadriceps ratio, position sense, and physical performance were not significantly different preoperatively, at 6 and 12 months after surgery. In intra-group analysis, muscle strength and position sense at each time point were not different in both groups. In physical performance, both groups resulted in improvement in the 6-min walk test, and only TKA group showed enhancement in stair climbing test.

CONCLUSIONS

Although theoretically plausible, bicompartmental knee arthroplasty was not superior in knee muscle strength and physical performance at 1 year compared with total knee arthroplasty.

Validity and reliability of isometric, isokinetic and isoinertial modalities for the assessment of quadriceps muscle strength in patients with total knee arthroplasty

Reliability of isometric, isokinetic and isoinertial modalities for quadriceps strength evaluation, and the relation between quadriceps strength and physical function was investigated in 29 total knee arthroplasty (TKA) patients, with an average age of 63 years. Isometric maximal voluntary contraction torque, isokinetic peak torque, and isoinertial one-repetition maximum load of the involved and uninvolved quadriceps were evaluated as well as objective (walking parameters) and subjective physical function (WOMAC). Reliability was good and comparable for the isometric, isokinetic, and isoinertial strength outcomes on both sides (intraclass correlation coefficient range: 0.947-0.966; standard error of measurement range: 5.1-9.3%). Involved quadriceps strength was significantly correlated to walking speed (r range: 0.641-0.710), step length (r range: 0.685-0.820) and WOMAC function (r range: 0.575-0.663), independent from the modality (P < 0.05). Uninvolved quadriceps strength was also significantly correlated to walking speed (r range: 0.413-0.539), step length (r range: 0.514-0.608) and WOMAC function (r range: 0.374-0.554) (P < 0.05), except for WOMAC function/isokinetic peak torque (P > 0.05). In conclusion, isometric, isokinetic, and isoinertial modalities ensure valid and reliable assessment of quadriceps muscle strength in TKA patients.