Early changes in muscle strength after total knee arthroplasty. A 6-month follow-up of 30 knees

The Impact of Acute Postoperative Pain in Developing Chronic Pain after Total Knee Arthroplasty

While total knee arthroplasties (TKAs) are performed with the intent to reduce pain, chronic postsurgical pain (CPSP) is one of the most well-documented complications that can occur following surgery. This study aimed to assess whether perioperative factors, focusing on acute postsurgical pain and perioperative opioid consumption, were associated with the development of chronic postsurgical pain. Under general anesthesia, 108 patients underwent TKA and were treated postoperatively with a multimodal analgesia approach. Numeric Rating Scale (NRS) pain scores at rest and with movement were recorded on postoperative days 0-3, 7, 14, and 30. Patients were sent a survey to assess chronic pain at months 22-66, which was examined as a single-group post hoc analysis. Based on the responses, patients were either classified into the CPSP or non-CPSP patient group. Chronic postsurgical pain was defined as an NRS score ≥ 4 with movement and the presence of resting pain. The primary outcome was a change in NRS. There were no differences in NRS pain scores with movement in the first 30 days postoperatively between patients with CPSP and without CPSP. Each unit increase in resting pain on postoperative days 3 and 14 was associated with significantly greater odds of CPSP presence (OR = 1.52; OR = 1.61, respectively), with a trend towards greater odds of CPSP at days 7 and 30 (OR = 1.33; OR = 1.43, respectively). We found that very intense pain in the initial phase seems to be related to the development of CPSP after TKA.

Effects of a Hybrid Teaching Program on Lower Limb Muscle Strength, Knee Function, and Depression in Older Adults After Total Knee Replacement: A Randomized Controlled Trial

The aim of the current study was to evaluate the effects of a nurse-led hybrid teaching program on lower limb strength, knee function, and depression in older adults after total knee replacement (TKR). This was a single-blind, randomized controlled trial. Fifty-two patients who underwent TKR were randomly assigned to either the experimental group (EG; n = 26), which received routine care plus 16 weeks of home rehabilitation through a hybrid teaching program, or the control group (CG; n = 26), which received routine care only. The intervention included pre-discharge face-to-face education, video instructions to follow at home after discharge, and four monthly telephone-based follow ups during the 16 weeks post-surgery. After the 16-week intervention, participants in the EG exhibited improved quadriceps strength, hamstring strength, and Knee Injury and Osteoarthritis Outcome Score (KOOS) compared to those in the CG. Generalized estimating equation analyses revealed a significant group-by-time interaction effect on quadriceps strength, overall KOOS score, and Geriatric Depression Scale-Short Form score. Findings suggest that a nurse-led hybrid teaching program enhances physical and psychological function after TKR when compared to routine care. This hybrid teaching program, involving exercise and postoperative education, proves to be a feasible and cost-effective intervention for improving outcomes in older adults following TKR. Health care teams should consider it as a viable home rehabilitation option for older adults who undergo TKR. [Research in Gerontological Nursing, 17(1), 31-40.].

The impact of preoperative muscle strength on postoperative walking ability in patients undergoing total knee arthroplasty

Although knee extensor muscle strength is strongly associated with postoperative walking ability (PWA) in patients undergoing total knee arthroplasty (TKA), few studies have considered the impact of both knee extensor and flexor muscle strength. This study aimed to determine whether operative side knee flexor and extensor muscle strength before surgery affects the PWA of patients who undergo TKA while accounting for potential covariates. This multicenter retrospective cohort study involved four university hospitals, and patients who underwent unilateral primary TKA were included. The outcome measure was the 5-m maximum walking speed test (MWS), which was completed 12 weeks postoperatively. Muscle strength was measured as the maximum isometric muscle strength required for knee flexor and extensor. Three multiple regression models with a progressively larger number of variables were developed to determine the predictors of 5-m MWS at 12 weeks post-TKA surgery. One hundred thirty-one patients who underwent TKA were enrolled in the study (men, 23.7%; mean age, 73.4 ± 6.9 years). Age, sex, operative side knee flexor muscle strength before surgery, Japanese Orthopaedic Association knee score, and preoperative walking ability were significantly associated with PWA in the final model of the multiple regression analysis ( R2  = 0.35). The current findings suggest that the operative side knee flexor muscle strength before surgery is a robust modifiable predictor of improved PWA. We believe that further validation is needed to determine the causal relationship between preoperative muscle strength and PWA.

Isokinetic knee muscle strength comparison after enhanced recovery after surgery (ERAS) versus conventional setup in total knee arthroplasty (TKA): a single blinded prospective randomized study

PURPOSE

Total knee arthroplasty (TKA) combined with the concept of enhanced recovery is of continued worldwide interest, as it is reported to improve early functional outcome and treatment quality without increasing complications. The aim of the study was to investigate isokinetic knee muscle strength after cemented TKA in combination with an enhanced recovery after surgery (ERAS) compared to a conventional setup.

METHODS

In the single blinded prospective randomized study, 52 patients underwent navigated primary cemented TKA within an ERAS (n = 30) or a conventional setup (n = 22). Preoperatively, five days and four weeks after surgery isokinetic knee muscle strength with BIODEX-type measuring device (peak torque in Nm, work in Joules and power in Watt) and subjective patient-related outcome measures (PROMs) were investigated.

RESULTS

The ERAS group showed significantly better outcomes in knee flexion at 180°/s (peak torque (Nm) p = 0.047, work (J) p = 0.040 and power (W) p = 0.016) 5 days postoperatively. The isokinetic measuring at knee extension 60°/s and 180°/s demonstrated no significant difference. The PROMs showed that patients were satisfied with the postoperative results in both groups. After 4 weeks, there was no longer a significant difference in isokinetic measuring at knee extension and flexion between the ERAS and conventional group.

CONCLUSIONS

TKA with the concept of ERAS improves excellent isokinetic outcome and patient satisfaction. The isokinetic muscle strength measurement can help patients and surgeons to modify expectations and improve patient satisfaction.

Tibio-Femoral Contact Force Distribution of Knee Before and After Total Knee Arthroplasty: Combined Finite Element and Gait Analysis

Objective

To assess the tibio‐femoral contact forces before and after total knee arthroplasty (TKA) in patients with knee osteoarthritis (KOA) by three‐dimensional (3D) finite element analysis (FEA) models and gait analysis.

Methods

Two hospitalized patients with Kellgren–Lawrence grade IV varus KOA and two healthy subjects were enrolled in this study. Both patients underwent unilateral TKA. FEA models were established based on CT and MR images of the knees of the patients with KOA and healthy subjects. Gait analysis was performed using a three‐dimensional motion capture system with a force plate. Three direction forces at the ankle joints were calculated by inverse dynamic analysis, which provided the load for the FEA models. The total contact forces of the knee joints were also calculated by inverse dynamic analysis to enable comparisons with the results from the FEA models. The total knee contact forces, maximum von Mises stress, and stress distribution of the medial plateau were compared between the patients and healthy subjects. The distributions of the medial plateau force at 2 and 6 months postoperatively were compared with the distributions of the forces preoperatively and those in the healthy subjects.

Results

During static standing, the medial plateau bore the most of the total contact forces in the knees with varus KOA (90.78% for patient 1 and 93.53% for patient 2) compared with 64.75 ± 3.34% of the total force in the healthy knees. At the first and second peaks of the ground reaction force during the stance phase of a gait cycle, the medial plateau bore a much higher percentage of contact forces in patients with KOA (74.78% and 86.48%, respectively, for patient 1; 70.68% and 83.56%, respectively, for patient 2) than healthy subjects (61.06% ± 3.43% at the first peak and 72.09% ± 1.83% at the second peak). Two months after TKA, the percentages of contact forces on the medial tibial plateau were 79.65%–85.19% at the first and second peaks of ground reaction forces during the stance phase of a gait cycle, and the percentages decreased to 53.99% – 68.13% 6 months after TKA.

Conclusion

FEA showed that TKA effectively restored the distribution of tibio‐femoral contact forces during static standing and walking, especially 6 months after the surgery. The changes in the gait were consistent with the changes in the contact force distribution calculated by the FEA model.

Total ankle arthroplasty: Strength, pain, and motion

BACKGROUND

While outcomes such as pain and ankle motion are well researched, information regarding the effect of total ankle arthroplasty on ankle plantarflexion strength is extraordinarily limited. The purpose of this study was to evaluate ankle plantarflexion strength before and after total ankle arthroplasty, and examine the interplay of pain, motion, and strength.

METHODS

This prospective case-control study included 19 patients with end-stage ankle arthritis who received a total ankle arthroplasty and 19 healthy control participants matched for age, sex, and body mass index. Pain was measured with a numeric pain rating scale. Passive sagittal plane ankle range of motion (°) and isokinetic ankle plantarflexion torque (Nm/kg) at 60 and 120°/s were measured with an instrumented dynamometer. t-tests or non-parametric tests were used to evaluate outcomes across time and between groups. Bivariate correlations were performed to evaluate the interplay of postoperative pain, motion, and torque.

FINDINGS

Patient pain and motion improved between the preoperative and six-month postoperative time points (d ≥ 0.7). Ankle plantarflexion torque was not different across time (d ≤ 0.5), but was lower than control group values postoperatively (d ≥ 1.4). Significant correlations between pain and motion (r = -0.48), but not torque (-0.11 ≤ r ≤ 0.13), were observed.

INTERPRETATION

Unchanged following surgery, impairments in muscle performance following total ankle arthroplasty do not appear to be changed by improved pain or motion. These findings provide impetus for postoperative strengthening interventions.

Potential Instability and Malfunction of Knee Joints with Vastus Medialis Impairment after Total Knee Arthroplasty

Four pairs of fresh-frozen cadaver knees (eight knees, four male knees) with a mean age of 72 ± 7 years were used for tests involving a customized simulator capable of controlling quadriceps loading conditions. The muscle force distribution of the quadriceps for the normal loading condition was applied on the basis of muscle cross-sectional area data, as previously reported (VM: 31 N; RF/VI: 49 N; VL: 45 N). To simulate vastus medialis (VM) impairment, we set the muscle force for VM in the muscle force distribution of the quadriceps at zero (VM: 0 N; RF/VI: 49 N; VL: 45 N). The joint reaction forces and moments on knee joints that underwent total knee arthroplasty (TKA) did not differ significantly according to VM impairment status for all flexion angles (p > 0.05). Nevertheless, the vectors of internal–external moments mostly showed a tendency for alteration from external to internal due to VM impairment. This tendency was evident in 9 cases in 12 total test pairs (with and without VM impairment). Furthermore, the vectors of the anterior–posterior reaction forces mostly showed a tendency to increase anteriorly due to VM impairment. This tendency was also evident in 9 cases in 12 total test pairs (with and without VM impairment). These results indicate that posterior dislocation of the tibia may be induced if VM impairment occurs after TKA. In conclusion, VM impairment in knee joints undergoing TKA may contribute to posterior dislocation of the tibia by a paradoxical roll-back with enhancements of the anterior joint reaction force and external moment during knee-joint flexion. Our findings may be valuable for understanding the mechanism of potential instability and malfunction due to VM impairment in knee joints after TKA, and may help to optimize clinical/rehabilitation training plans to improve the prognosis (stability and function) of knee joints undergoing TKA.

Essential amino acid supplementation alters the p53 transcriptional response and cytokine gene expression following total knee arthroplasty

Reducing muscle atrophy following orthopedic surgery is critical during the postoperative period. Our previous work in patients who underwent total knee arthroplasty (TKA) showed that the vast majority of atrophy occurs within 2 wk following surgery and that essential amino acid (EAA) supplementation attenuates this atrophy. We used RNA-sequencing (RNA-seq) to identify genes associated with atrophy after TKA with and without EAAs. Analysis of overrepresented gene-ontology terms revealed that p53 signaling and the cytokine-cytokine receptor pathways were highly upregulated after TKA. Relative to the placebo group, the EAA group had altered expression of p53 regulators such as MDM2. This altered expression may account for differences between groups in timing of upregulation of some p53 targets such as apoptosis genes, and may account for the reduction in muscle loss in the subjects receiving EAAs. Furthermore, we observed altered expression of a large number of cytokine-signaling genes including TNFRSF12A, which plays a critical role in muscle atrophy, myogenesis, fibrosis, and the noncanonical NF-κB pathway.NEW & NOTEWORTHY Total knee arthroplasty is the most frequently performed inpatient surgical procedure for those over 45 yr in the United States. Following surgery, patients lose a large amount of muscle, which impacts functional mobility. Previously, our laboratory found that supplementing patients' diets with essential amino acids (EAAs) reduces postsurgical muscle loss. Here, our goal was to characterize the transcriptional changes associated with surgery with and without EAA supplementation to uncover the underlying mechanisms by which EAAs attenuate this muscle loss.

Short-term functional advantages after medial unicompartmental versus total knee arthroplasty

BACKGROUND

There are many uncertainties about the advantages and disadvantages of using unicompartmental (UKA) versus total knee arthroplasty (TKA) to treat patients with knee osteoarthritis. It is important to have sufficient early postoperative quadriceps strength for long-term, self-reported and gait-related outcomes after knee arthroplasty, but very limited comparative data exist regarding UKA and TKA patients.

METHODS

This study assessed isometric quadriceps strength, spatio-temporal gait parameters (walking speed, step length, single-limb support phase) and self-reported outcomes (pain, function, stiffness) in 18 TKA and 18 UKA patients six months after surgery, as well as in 18 healthy controls.

RESULTS

Quadriceps strength of TKA, but not of UKA patients, was lower than that of controls (P < 0.05). UKA patients demonstrated better gait function in terms of a longer single-limb support phase than TKA patients (P < 0.01), which agreed with better self-reported pain (P < 0.05), function (P < 0.01) and stiffness (P < 0.05) scores compared to TKA patients.

CONCLUSIONS

Six months after surgery, UKA patients showed better short-term quadriceps strength and gait function compared to TKA patients, together with less self-reported knee pain and stiffness. Patients eligible for UKA may experience less functional impairments compared to those who require TKA.

Essential Amino Acid Supplementation Mitigates Muscle Atrophy After Total Knee Arthroplasty: A Randomized, Double-Blind, Placebo-Controlled Trial

Background

Substantial muscle atrophy occurs after total knee arthroplasty (TKA), resulting in decreased strength and impaired mobility. We sought to determine whether perioperative supplementation with essential amino acids (EAA) would attenuate muscle atrophy following TKA and whether the supplements were safe for ingestion in an older surgical population.

Methods

We performed a double-blind, placebo-controlled, randomized trial of 39 adults (age range, 53 to 76 years) undergoing primary unilateral TKA who ingested 20 g of EAA (n = 19) or placebo (n = 20) twice daily for 7 days preoperatively and for 6 weeks postoperatively. At baseline and 6 weeks postoperatively, magnetic resonance imaging (MRI) scans were obtained to measure quadriceps and hamstrings muscle volume. Secondary outcomes included functional mobility and strength. Data on physical activity, diet, and patient-reported outcomes (Veterans RAND 12-Item Health Survey and Knee injury and Osteoarthritis Outcome Score) were collected. Safety was determined through blood tests evaluating blood urea nitrogen, creatinine, creatinine clearance, homocysteine, and renal and liver function. Laboratory values at baseline, on the day of surgery, and at 2 days, 2 weeks, and 6 weeks postoperatively were compared between treatment groups. Analysis of covariance models, with baseline values as covariates, were used to evaluate outcomes between treatment groups. P values were adjusted for multiple tests.

Results

Compared with baseline, the EAA group had significantly less decrease in mean quadriceps muscle volume compared with the placebo group in the involved leg (-8.5% ± 2.5% compared with -13.4% ± 1.9%; p = 0.033) and the contralateral leg (-1.5% ± 1.6% compared with -7.2% ± 1.4%; p = 0.014). The hamstrings also demonstrated a greater muscle-volume-sparing effect for the EAA group than for the placebo group in the involved leg (-7.4% ± 2.0% compared with -12.2% ± 1.4%; p = 0.036) and contralateral leg (-2.1% ± 1.3% compared with -7.5% ± 1.5%; p = 0.005). There were no differences between the groups in terms of functional measures or strength. Blood chemistry values varied significantly between assessments periods but did not statistically differ between groups.

Conclusions

The results of the present study suggest that EAA supplementation is safe and reduces the loss of muscle volume in older adults recovering from TKA.

Level of Evidence

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Effects of Early Combined Eccentric-Concentric Versus Concentric Resistance Training Following Total Knee Arthroplasty

Objective

To investigate the effects of early combined eccentric-concentric (ECC-CON) or concentric (CON) resistance training following total knee arthroplasty (TKA).

Methods

Patients who underwent a primary TKA were randomly assigned to an ECC-CON group (n=16) or a CON group (n=18). All patients received early, progressive resistance training with five sessions per week for 2 weeks starting 2 weeks after TKA. Isometric knee flexor and extensor strength of the surgical and non-surgical knees, instrumental gait analysis for spatiotemporal parameters, 6-Minute Walk Test (6MWT), Timed Up and Go Test (TUG), Timed Stair Climbing Test (SCT) were used to evaluate performance-based physical function. The Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) and EuroQOL five dimensions (EQ-5D) questionnaire were used to evaluate self-reported physical function and self-reported quality of life. All patients underwent these evaluations before and 1 month after TKA.

Results

The ECC-CON group showed clinically meaningful improvements in extensor peak torque (PT) of the non-surgical knee, gait speed, and 6MWT from preoperative values. The CON group had an increase in H/Q ratio of the surgical knee and improvement in SCT-ascent postoperatively. Both groups showed significant improvements in WOMAC-Pain, function, and EQ-5D scores. Although extensor PT of the surgical knee did not reach the preoperative level in either group, the postoperative change was significantly less in the ECC-CON group than the CON group.

Conclusion

Early combined ECC-CON resistance training minimizes the loss in quadriceps strength of the surgical knee and improves endurance and gait speed after TKA.

Semimembranosus Release for Medial Soft Tissue Balancing Does Not Weaken Knee Flexion Strength in Patients Undergoing Varus Total Knee Arthroplasty

BACKGROUND

The sequential medial release technique including semimembranosus (semiM) release is effective and safe during varus total knee arthroplasty (TKA). However, there are concerns about weakening of knee flexion strength after semiM release. We determined whether semiM release to balance the medial soft tissue decreased knee flexion strength after TKA.

METHODS

Fifty-nine consecutive varus knees undergoing TKA were prospectively enrolled. A 3-step sequential release protocol which consisted of release of (1) the deep medial collateral ligament (dMCL), (2) the semiM, and (3) the superficial medial collateral ligament based on medial tightness. Gap balancing was obtained after dMCL release in 31 knees. However, 28 knees required semiM release or more after dMCL release. Isometric muscle strength of the knee was compared 6 months postoperatively between the semiM release and semiM nonrelease groups. Knee stability and clinical outcomes were also compared.

RESULTS

No differences in knee flexor or extensor peak torque were observed between the groups 6 months postoperatively (P = .322 and P = .383, respectively). No group difference was observed in medial joint opening angle on valgus stress radiographs (P = .327). No differences in the Knee Society or Western Ontario and McMaster Universities Osteoarthritis Index scores were detected between the groups (P = .840 and P = .682, respectively).

CONCLUSION

These results demonstrate that semiM release as a sequential step to balance medial soft tissue in varus knees did not affect knee flexion strength after TKA.

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.

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.

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.

Better quadriceps recovery after minimally invasive total knee arthroplasty

PURPOSE

The proponents of minimally invasive total knee arthroplasty (TKA) have reported better functional recovery than conventional TKA. In most of the previous studies, the results were shown with the relatively subjective methods. We investigated the objective results with a dynamometry in this prospective randomized study. It was hypothesized that minimally invasive TKA would have a better and earlier recovery of quadriceps force in terms of the objective numeric data.

METHODS

Sixty-six TKAs were prospectively randomized into two groups. Thirty-three knees underwent minimally invasive TKA using mini-midvastus approach and 33 knees underwent conventional TKA using medial parapatellar approach. The quadriceps force was assessed using a dynamometer. The data were collected preoperatively and at postoperative 6 weeks, 3 months, 6 months and 1 year consecutively.

RESULTS

The mean of quadriceps force in minimally invasive TKA group at postoperative 6 weeks was greater than conventional TKA after removing the covariate (preoperative quadriceps force) with analysis of covariance (P = 0.002), but thereafter, the difference was not significant till 1 year. Meanwhile, with repeated measures analysis of variance, conventional TKA group had greater quadriceps recovery than minimally invasive TKA group during postoperative 6 weeks to 3 months (P = 0.035). The proportion of patients unable to recover the quadriceps force to their preoperative levels by 1 year postoperatively was similar in two groups.

CONCLUSION

Minimally invasive TKA has benefit in quadriceps recovery at earlier rehabilitation period although catch-up recovery in conventional TKA was accelerated from the postoperative 6 weeks to 3 months. It may support the concept of early return to full activity after minimally invasive TKA, and patients might get back early to normal life.

EFFECTS OF ADDING BIOFEEDBACK TRAINING TO ACTIVE EXERCISES AFTER TOTAL KNEE ARTHROPLASTY

The purpose of this study was to evaluate the effects of adding biofeedback training to active exercise training on quadriceps torque, voluntary activation and functional activity after total knee arthroplasty (TKA). A total of 45 patients with unilateral TKA participated in this study; their ages ranged from 58 to 67 years. They were assigned randomly to two groups. Group I comprised 21 patients who practiced an active exercise training program for 30 to 45 min/session, two sessions/week, for 4 months. Group II contained 24 patients who practiced biofeedback training in addition to the active exercise training program for 30 to 45 min/session, two sessions/week, for 4 months. Isometric peak torque of the quadriceps, voluntary activation and knee functional activity were measured. The results revealed significant improvements in quadriceps torque, voluntary activation and knee functional activity for both groups, with more improvement in knee functional activities in group II. There were nonsignificant differences between the two groups in both quadriceps peak torque and voluntary activation after training (p > 0.05). Conclusion: An active exercise program can enhance quadriceps peak torque, voluntary activation and knee functional activity after unilateral TKA. The addition of biofeedback training increases the benefits for the knee functional activity of a patient.

Increased turn/amplitude parameters following subvastus approach in total knee arthroplasty

PURPOSE

To compare the improvement of the vastus medialis component of the quadriceps muscle electrophysiologically after the subvastus and medial parapatellar approaches in total knee arthroplasty (TKA).

METHODS

A total 26 patients that underwent primary unilateral in TKA were included into the study. TKAs were carried out via subvastus approach in 15 patients, while 11 patients were operated via medial parapatellar approach. The electrophysiological evaluations were carried out blindly with regard to the type of the surgical approach before the operation and at 6th week post-operatively. Non-surgical side was also evaluated as a control. Assessments were patellar tendon reflex analysis, motor unit potential analysis and interference pattern analysis (IPA) including turn-amplitude analysis and IPA during maximum contraction.

RESULTS

When they were compared to the pre-operative values, "the total mean amplitude" and "the mean turn/sec" parameters were significantly increased in group of subvastus approach (p = 0.017 and p = 0.009, respectively) at the post-operative 6th week. We would not be able to find any difference regarding the other electrophysiological parameters. There was also no significant difference between groups.

CONCLUSION

If there was no significant difference in all the electrophysiological parameters, the increase in turn-amplitude analysis in the group of subvastus approach would be considered as an indicator of a faster functional improvement of knee extensor mechanism in these cases.

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.

Essential amino acid supplementation in patients following total knee arthroplasty

BACKGROUND

By the year 2030, 3.48 million older U.S. adults are projected to undergo total knee arthroplasty (TKA). Following this surgery, considerable muscle atrophy occurs, resulting in decreased strength and impaired functional mobility. Essential amino acids (EAAs) have been shown to attenuate muscle loss during periods of reduced activity and may be beneficial for TKA patients.

METHODS

We used a double-blind, placebo-controlled, randomized clinical trial with 28 older adults undergoing TKA. Patients were randomized to ingest either 20 g of EAAs (n = 16) or placebo (n = 12) twice daily between meals for 1 week before and 2 weeks after TKA. At baseline, 2 weeks, and 6 weeks after TKA, an MRI was performed to determine mid-thigh muscle and adipose tissue volume. Muscle strength and functional mobility were also measured at these times.

RESULTS

TKA patients receiving placebo exhibited greater quadriceps muscle atrophy, with a -14.3 ± 3.6% change from baseline to 2 weeks after surgery compared with -3.4 ± 3.1% for the EAA group (F = 5.16, P = 0.036) and a -18.4 ± 2.3% change from baseline to 6 weeks after surgery for placebo versus -6.2 ± 2.2% for the EAA group (F = 14.14, P = 0.001). EAAs also attenuated atrophy in the nonoperated quadriceps and in the hamstring and adductor muscles of both extremities. The EAA group performed better at 2 and 6 weeks after surgery on functional mobility tests (all P < 0.05). Change in quadriceps muscle atrophy was significantly associated with change in functional mobility (F = 5.78, P = 0.021).

CONCLUSION

EAA treatment attenuated muscle atrophy and accelerated the return of functional mobility in older adults following TKA.

TRIAL REGISTRATION

Clinicaltrials.gov NCT00760383.

Patellar eversion does not adversely affect quadriceps recovery following total knee arthroplasty

Although avoiding patellar eversion during a total knee arthroplasty (TKA) has theoretical benefit in quadriceps recovery, there has been paucity of supportive objective clinical results. We prospectively designed the study whether TKA without patellar eversion has better quadriceps recovery in an objective, dynamometer study. Seventy-two knees undergoing TKA with midvastus approach were randomized into two groups according to patellar eversion or not. Clinical data and objective quadriceps recovery using a dynamometer were investigated preoperatively and postoperative at 6weeks, 3months, 6months and 1year. There were no statistical differences between two groups throughout the follow-up periods in recovery of quadriceps force or power and clinical data. Choosing to evert patella during TKA using midvastus approach would not adversely affect postoperative quadriceps recovery.

Maximal voluntary isokinetic knee flexion torque is associated with femoral shaft bone strength indices in knee replacement patients

It is currently unknown whether knee replacement-associated bone loss is modified by rehabilitation programs. Thus, a sample of 45 (18 men and 25 women) persons with unilateral knee replacement were recruited; age 66 years (sd 6), height 169 cm (sd 8), body mass 83 kg (sd 15), time since operation 10 months (sd 4) to explore the associations between maximal torque/power in knee extension/flexion and femoral mid-shaft bone traits (Cortical cross-sectional area (CoA, mm(2)), cortical volumetric bone mineral density (CoD, mg/mm(3)) and bone bending strength index (SSI, mm(3))). Bone traits were calculated from a single computed tomography slice from the femoral mid-shaft. Pain in the operated knee was assessed with the WOMAC questionnaire. Stepwise regression models were built for the operated leg bone traits, with knee extension and flexion torque and power, age, height, body mass, pain score and time since operation as independent variables. CoA was 2.3% (P=0.015), CoD 1.2% (P<0.001) and SSI 1.6% (P=0.235) lower in the operated compared to non-operated leg. The overall proportions of the variation explained by the regression models were 50%, 29% and 55% for CoA, CoD and SSI, respectively. Body mass explained 12% of Coa, 11% of CoD and 11% of SSI (P≤0.003). Maximal knee flexion torque explained 38% of Coa, 7% of CoD and 44% of SSI (p≤0.047). For CoD time since operation also became a significant predictor (11%, P=0.045). Knee flexion torque of the operated leg was positively associated with bone strength in the operated leg. Thus, successful rehabilitation may diminish bone loss in the operated leg.

Anabolic steroids in patients undergoing total knee arthroplasty

OBJECTIVES

To systematically review the evidence for using anabolic-androgenic steroids (AAS) to aid rehabilitation following total knee replacement (TKR).

DESIGN

Systematic review of all clinical study designs.

DATA SOURCES

MEDLINE, EMBASE, AMED, CINAHL and the Cochrane Library were searched from inception to August 2012.

ELIGIBILITY CRITERIA

All clinical study designs without language or patient demographic limits.

OUTCOME MEASURES

All functional, physiological and administrative outcomes as well as reporting of adverse events.

RESULTS

Only two small randomised controlled trials satisfied the inclusion criteria. Statistically significant improvements were reported in the AAS group for quadriceps strength at 3 (p=0.02), 6 (p=0.01) and 12 (p=0.02) months, Functional Independence Measure score at 35 days (p=<0.05) and Knee Society Score at 6 weeks (p=0.02), 6 months (p=0.04) and 12 months (p=0.03). However, differences in hamstring strength, bone mineral density, sit-to-stand testing, walking speed, length of hospital stay and need for further inpatient rehabilitation did not reach statistical significance. There were no reported adverse events.

CONCLUSIONS

There is insufficient evidence to recommend routine administration of AAS to patients undergoing TKR. However, pilot data suggest that AAS can be administered safely and may improve important postoperative outcome measures. This justifies a randomised trial sufficiently powered to identify between-group differences likely to be of clinical significance.

The effectiveness of minimally invasive total knee arthroplasty to preserve quadriceps strength: a randomized controlled trial

We performed a single-center, randomized, double-blind study to compare muscle strength in patients who had undergone primary total knee arthroplasty (TKA), performed using either a minimally invasive or a conventional surgical technique. We evaluated 30 knees in healthy age-matched subjects, 22 knees after conventional TKA (conventional group), and 23 knees after minimally invasive surgery TKA (MIS group). The Hospital for Special Surgery (HSS) score, Oxford knee score (OKS), and isokinetic (60º/s) muscle strength were evaluated the day before surgery and 3, 6, and 12 months after surgery. HSS and OKS improved significantly over time during follow-up (p<0.001), but there was no significant difference between the groups (p>0.05). The extensor peak torque (EPT) and flexor peak torque (FPT) improved significantly over time (p<0.001) and EPT was greater in the MIS group than in the conventional group during the follow-up period (p<0.05). There was no difference in FPT and the hamstring-to-quadriceps ratio between the groups. Although MIS patients had a significant deficit in extensor strength following TKA, compared with healthy controls, this approach offers a significant improvement in extensor muscle strength over conventional surgery. These results suggest that the MIS approach results in better outcomes with regard to maintaining extensor strength than the conventional surgical approach.

Reliability of maximal isometric knee strength testing with modified hand-held dynamometry in patients awaiting total knee arthroplasty: useful in research and individual patient settings? A reliability study

BACKGROUND

Patients undergoing total knee arthroplasty (TKA) often experience strength deficits both pre- and post-operatively. As these deficits may have a direct impact on functional recovery, strength assessment should be performed in this patient population. For these assessments, reliable measurements should be used. This study aimed to determine the inter- and intrarater reliability of hand-held dynamometry (HHD) in measuring isometric knee strength in patients awaiting TKA.

METHODS

To determine interrater reliability, 32 patients (81.3% female) were assessed by two examiners. Patients were assessed consecutively by both examiners on the same individual test dates. To determine intrarater reliability, a subgroup (n = 13) was again assessed by the examiners within four weeks of the initial testing procedure. Maximal isometric knee flexor and extensor strength were tested using a modified Citec hand-held dynamometer. Both the affected and unaffected knee were tested. Reliability was assessed using the Intraclass Correlation Coefficient (ICC). In addition, the Standard Error of Measurement (SEM) and the Smallest Detectable Difference (SDD) were used to determine reliability.

RESULTS

In both the affected and unaffected knee, the inter- and intrarater reliability were good for knee flexors (ICC range 0.76-0.94) and excellent for knee extensors (ICC range 0.92-0.97). However, measurement error was high, displaying SDD ranges between 21.7% and 36.2% for interrater reliability and between 19.0% and 57.5% for intrarater reliability. Overall, measurement error was higher for the knee flexors than for the knee extensors.

CONCLUSIONS

Modified HHD appears to be a reliable strength measure, producing good to excellent ICC values for both inter- and intrarater reliability in a group of TKA patients. High SEM and SDD values, however, indicate high measurement error for individual measures. This study demonstrates that a modified HHD is appropriate to evaluate knee strength changes in TKA patient groups. However, it also demonstrates that modified HHD is not suitable to measure individual strength changes. The use of modified HHD is, therefore, not advised for use in a clinical setting.

Low cost continuous femoral nerve block for relief of acute severe cancer related pain due to pathological fracture femur

Pathological fractures in cancer patient cause severe pain that is difficult to control pharmacologically. Even with good pain relief at rest, breakthrough and incident pain can be unmanageable. Continuous regional nerve blocks have a definite role in controlling such intractable pain. We describe two such cases where severe pain was adequately relieved in the acute phase. Continuous femoral nerve block was used as an efficient, cheap and safe method of pain relief for two of our patients with pathological fracture femur. This method was proved to be quite efficient in decreasing the fracture-related pain and improving the level of well being.

Time course of quad strength, area, and activation after knee arthroplasty and strength training

INTRODUCTION

changes in strength, activation, and morphology of the quadriceps femoris muscle group were assessed in 61 individuals that underwent unilateral total knee arthroplasty, with progressive postoperative strength training, for primary knee osteoarthritis.

METHODS

assessments of these three parameters were made at four time points (preoperatively and 4, 12, and 52 wk postoperatively). Maximal voluntary knee extension strength was recorded using an electromechanical dynamometer, and voluntary muscle activation was measured using a burst superimposition technique. Lean muscle cross-sectional area (CSA) was determined using magnetic resonance imaging.

RESULTS

preoperatively, the surgical limb was significantly weaker and smaller than the nonsurgical limb. Strength, voluntary muscle activation, and CSA of the quadriceps femoris significantly improved over the study period. At 52 wk, the surgical limb was still significantly smaller than the nonsurgical limb but had greater levels of voluntary muscle activation. In the nonsurgical limb, CSA was the primary determinant of strength across all time points, with voluntary muscle activation progressively contributing more from the preoperative assessment (R = 0.11) to the assessment 52 wk postoperatively (R = 0.26). In the surgical limb, voluntary muscle activation was the primary determinant of strength preoperatively and 4 wk postoperatively (R = 0.38 and 0.41, respectively), whereas CSA was the primary determinant of quadriceps strength 12 and 52 wk postoperatively (R = 0.44).

CONCLUSION

resolving the impairments in voluntary muscle activation after total knee arthroplasty may be necessary before visible gains in strength and muscle hypertrophy are evident.

An Eccentrically Biased Rehabilitation Program Early after TKA Surgery

Rehabilitation services are less-studied aspects of the management following total knee arthroplasty (TKA) despite long-term suboptimal physical functioning and chronic deficits in muscle function. This paper describes the preliminary findings of a six-week (12 session) eccentrically-biased rehabilitation program targeted at deficits in physical function and muscle function, initiated one month following surgery. A quasiexperimental, one group, pretest-posttest study with thirteen individuals (6 female, 7 male; mean age 57 ± 7 years) examined the effectiveness of an eccentrically-biased rehabilitation program. The program resulted in improvements in the primary physical function endpoints (SF-36 physical component summary and the six-minute walk test) with increases of 59% and 47%, respectively. Muscle function endpoints (knee extension strength and power) also increased 107% and 93%, respectively. Eccentrically-biased exercise used as an addition to rehabilitation may help amplify and accelerate physical function following TKA surgery.

Benefits of starting rehabilitation within 24 hours of primary total knee arthroplasty: randomized clinical trial

Objective: To compare the benefits of initiating rehabilitation treatment within 24 hours versus 48–72 hours after total knee arthroplasty for osteoarthritis.

Design: Experimental study with clinical trial design.

Subjects: Patients undergoing primary total knee arthroplasty for osteoarthritis were randomly assigned to experimental (n = 153) and control (n = 153) groups.

Interventions: Rehabilitation was started within 24 hours post surgery in the experimental group and between 48 hours and 72 hours post surgery in the controls.

Main measures: Measurement variables included joint range of motion, muscle strength, pain, autonomy, gait and balance.

Results: In comparison with the controls, the experimental group showed significantly shorter hospital stay (by (mean ± standard deviation) 2.09 ± 1.45 days; P < 0.001), fewer rehabilitation sessions until medical discharge (by 4.95 ± 2.34; P < 0.001), lesser pain (by 2.36 ± 2.47 points; P < 0.027), greater joint range of motion in flexion (by 16.29 ± 11.39 degrees; P < 0.012) and extension (by 2.12 ± 3.19; P < 0.035), improved strength in quadriceps (by 0.98 ± 0.54; P < 0.042) and hamstring muscles (by 1.05 ± 0.72; P < 0.041), and higher scores for gait (P < 0.047) and balance (P < 0.045).

Conclusion: Initiation of rehabilitation within 24 hours after total knee arthroplasty reduces the mean hospital stay and number of sessions required to achieve autonomy and normal gait and balance.

Contribution of hip abductor strength to physical function in patients with total knee arthroplasty

BACKGROUND

Investigating modifiable factors that contribute to functional limitations in patients with total knee arthroplasty (TKA) may guide changes in rehabilitation protocols and improve functional outcomes. Whereas quadriceps muscle weakness has been demonstrated to contribute to functional limitations in TKA, the role of hip abductor weakness has not received attention.

OBJECTIVE

The purpose of this study was to determine whether hip abductor strength (force-generating capacity) contributes to physical function beyond what can be explained by quadriceps muscle strength in patients after a TKA.

DESIGN

A cross-sectional design was used in the study.

SETTING

The study was conducted in a clinical laboratory at an academic center.

PATIENTS

Thirty-one people with TKA (74% female; mean age=68 years, SD=8; mean body mass index=31 kg/m(2), SD=5) participated in the study.

MEASUREMENTS

Strength of quadriceps muscles and hip abductors was measured using an isokinetic dynamometer. Performance-based physical function was assessed with 4 measures: self-selected walking speed, the Figure-of-8 Walk Test, the Stair Ascend/Descend Test, and the 5-Chair Rise Test. Self-reported physical function was assessed with the Western Ontario and McMaster Universities Osteoarthritis Index Physical Function Subscale.

RESULTS

In hierarchical regression models, after accounting for demographic and anthropometric factors, quadriceps muscle strength was associated with performance on the Stair Ascend/Descend Test. After accounting for demographic, anthropometric, and quadriceps strength, hip abductor strength was associated with performance on the Stair Ascend/Descend Test, the Figure-of-8 Walk Test, and the 5-Chair Rise Test.

LIMITATIONS

The study design precluded ascertainment of causal relationships.

CONCLUSIONS

After TKA, hip abductor strength influenced physical function in participants more than did demographic or anthropometric measures or quadriceps strength. Longitudinal studies with larger samples are warranted. If findings are replicated, they will justify targeting the hip abductors during rehabilitation after TKA.

Internet-based outpatient telerehabilitation for patients following total knee arthroplasty: a randomized controlled trial

BACKGROUND

total knee arthroplasty is an effective means for relieving the symptoms associated with degenerative arthritis of the knee. Rehabilitation is a necessary adjunct to surgery and is important in regaining optimum function. Access to high-quality rehabilitation services is not always possible, especially for those who live in rural or remote areas. The aim of this study was to evaluate the equivalence of an Internet-based telerehabilitation program compared with conventional outpatient physical therapy for patients who have had a total knee arthroplasty.

METHODS

this investigation was a single-blinded, prospective, randomized, controlled noninferiority trial. Sixty-five participants were randomized to receive a six-week program of outpatient physical therapy either in the conventional manner or by means of an Internet-based telerehabilitation program. The primary outcome measure was the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) measured at baseline and six weeks by a blinded independent assessor. Secondary outcomes included the Patient-Specific Functional Scale, the timed up-and-go test, pain intensity, knee flexion and extension, quadriceps muscle strength, limb girth measurements, and an assessment of gait. Noninferiority was assessed through the comparison of group differences with a noninferiority margin and with linear mixed model statistics.

RESULTS

baseline characteristics between groups were similar, and all participants had significant improvement on all outcome measures with the intervention (p < 0.01 for all). After the six-week intervention, participants in the telerehabilitation group achieved outcomes comparable to those of the conventional rehabilitation group with regard to flexion and extension range of motion, muscle strength, limb girth, pain, timed up-and-go test, quality of life, and clinical gait and WOMAC scores. Better outcomes for the Patient-Specific Functional Scale and the stiffness subscale of the WOMAC were found in the telerehabilitation group (p < 0.05). The telerehabilitation intervention was well received by participants, who reported a high level of satisfaction with this novel technology.

CONCLUSIONS

the outcomes achieved via telerehabilitation at six weeks following total knee arthroplasty were comparable with those after conventional rehabilitation.

LEVEL OF EVIDENCE

therapeutic Level I. See Instructions to Authors for a complete description of levels of evidence.

Quadriceps and hamstrings muscle dysfunction after total knee arthroplasty

BACKGROUND/RATIONALE

Although TKA reliably reduces pain from knee osteoarthritis, full recovery of muscle strength and physical function to normal levels is rare. We presumed that a better understanding of acute changes in hamstrings and quadriceps muscle performance would allow us to enhance early rehabilitation after TKA and improve long-term function.

QUESTIONS/PURPOSES

The purposes of this study were to (1) evaluate postoperative quadriceps and hamstrings muscle strength loss after TKA and subsequent recovery using the nonoperative legs and healthy control legs for comparison, and (2) measure hamstrings coactivation before and after TKA during a maximal isometric quadriceps muscle contraction and compare with nonoperative and healthy control legs.

METHODS

We prospectively followed 30 patients undergoing TKA at 2 weeks preoperatively and 1, 3, and 6 months postoperatively and compared patient outcomes with a cross-sectional cohort of 15 healthy older adults. Bilateral, isometric strength of the quadriceps and hamstrings was assessed along with EMG measures of hamstrings coactivation during a maximal isometric quadriceps contraction.

RESULTS

There were no differences in strength loss or recovery between the quadriceps and hamstrings muscles of the operative leg throughout the followup, although differences existed when compared with nonoperative and healthy control legs. Hamstrings muscle coactivation in the operative leg during a maximal quadriceps effort was elevated at 1 month (144.5%) compared to the nonoperative leg.

CONCLUSIONS

Although quadriceps dysfunction after TKA typically is recognized and addressed in postoperative therapy protocols, hamstrings dysfunction also is present and should be addressed.

CLINICAL RELEVANCE

Quadriceps and hamstrings muscle strengthening should be the focus of future rehabilitation programs to optimize muscle function and long-term outcomes.

On the role of knee joint in balance control and postural strategies: effects of total knee replacement in elderly subjects with knee osteoarthritis

This study aimed to evaluate the role of the knee joint in the neurosensory organization of balance control and the generation of postural sensorimotor strategies. Ten patients, aged over 60 years and having undergone unilateral total knee replacement (TKR) for osteoarthritis, and 20 controls were submitted to static and dynamic posturographic tests and to a sensory organization test (SOT) aiming at evaluating postural control in quiet stance and during movement. The patients were submitted to these evaluations after the disappearance of pain (TKR(1)) and at the end of a 6-week rehabilitation program (TKR(2)). Balance control being greatly improved at TKR2 compared to TKR1, the patients attain a quality of postural regulation similar to that of the controls; some postural abnormalities did however persist for the static test. Moreover, SOT values at TKR(2) close to those of the controls highlighted an improvement in motor response, better management in altered proprioceptive information situations, and greater use of the ankle to control balance. This model of intervention on the knee joint, namely knee replacement due to osteoarthritis, has shown that gradual functional sensorimotor restoration after TKR, due to intrasensory proprioceptive compensation either at knee, or at other joint levels (hip/ankle), improves dynamic balance control. This reacquisition allows the knee joint to recover its corrective compensatory role in postural regulation allowing, through neuroplasticity, the modification of muscular activation sequences and, thus, the implementation of anticipatory sensorimotor strategies.

Absence of combined effects of anemia and bilateral surgical status on inpatient rehabilitation outcomes following total knee arthroplasty

PURPOSE

To examine the effects of anemia on inpatient rehabilitation outcomes following unilateral and bilateral total knee arthroplasty (TKA).

METHOD

This was a multicenter, retrospective study from 15 inpatient rehabilitation facilities. Patients (N = 5421) with very low hematocrit (Hct <30%), low Hct (30-36% women, 30-41% men), or normal Hct (>36% women, 41% men) were included. Inpatient rehabilitation occurred following TKA. Functional independence measure (FIM) scores, length of stay (LOS), itemized hospital charges, discharge destination were main outcomes.

RESULTS

LOS was 13% longer and hospital charges were 12.5-18.0% higher in the very low Hct than remaining groups (p = 0.0001). The FIM score and subscores for walking, stair climbing, bathing, transfers, and dressing changes were comparable for all Hct groups for the overall score. Hct <30% did not correspond to worse outcomes in patients with bilateral surgeries compared with unilateral surgeries; total FIM scores improved 47-53% across all Hct groups, regardless of bilateral surgical status. Discharge to home ranged 92.6-94.7% across all Hct groups (p > 0.05).

CONCLUSIONS

Rehabilitation teams can expect comparable functional improvements and discharge to home in anemic and non-anemic patients with either unilateral or bilateral surgeries without hematologic correction in the rehabilitation setting, but might need an additional day to accomplish these outcomes.

Functional performance with a single-radius femoral design total knee arthroplasty

BACKGROUND

Better muscular recovery of the extensor mechanism after TKA is claimed by femoral designs based on a sagittal single radius.

QUESTIONS/PURPOSES

We aimed to compare postoperative knee performance through the Knee Society scores, flexor and extensor muscle function, stability, and gait of a series of patients receiving a posterior stabilized, cemented TKA, with a single-radius femoral design.

METHODS

We compared a series of patients treated with a single-radius femoral design TKA to a simultaneous series of patients receiving a multiradius femoral design. Both groups were similar in demographics and preoperative Knee Society scores. The clinical pathways were identical. Outcome assessment included Knee Society scores, isokinetic assessment, stabilometry, and gait cycle analysis.

RESULTS

We observed higher functional Knee Society scores (86.6 +/- 1.89 versus 80.3 +/- 1.90), fewer physiotherapy sessions (19.9 +/- 4.65 versus 22.2 +/- 3.34), and less time with two crutches (3.5 +/- 1.2 versus 5.2 +/- 1.04 weeks) for patients receiving the single-radius design. Isokinetic evaluation showed decreased flexion peak torque (40.3 +/- 7.9 versus 48.7 +/- 9.6), increased extension peak torque (77.2 +/- 16.1 versus 69.1 +/- 14.4), and lower flexor/extensor ratio (0.5 +/- 0.08 versus 0.7 +/- 0.1) in patients with the single-radius design. Stabilometry showing less relative oscillation, and gait cycle indirectly confirmed better support in the limb with the single-radius design.

CONCLUSIONS

The studied single-radius femoral design showed better functional short-term outcome and better extensor performance.

LEVEL OF EVIDENCE

Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Closed-chain exercise after simultaneous bilateral knee replacement surgery: a case report

The purpose of this case report was to present a method for assessing entire lower extremity performance and describe a Medical Exercise Therapy (MET) training program early after simultaneous bilateral total knee replacement (TKR). We also documented perceived function, mobility, and weight-bearing ability during functional tasks. The patient was a 50-year-old male who underwent a simultaneous bilateral procedure and began physical therapy (PT) 16 days postsurgery. Lower extremity performance (weight, repetitions, and load*volume) was assessed weekly using a one-legged horizontal press. Perceived physical abilities, mobility, and body weight placed over each limb during a sit to stand and a squat at two different flexion angles were assessed. At discharge load*volume for the weakest limb was 87% of the strongest side. At discharge, sit-to-stand, and 30 and 60 degree squat asymmetry ranged from 4% to 6%. Perceived abilities and mobility improved from initial visit to discharge. The patient was able to tolerate the closed-chain assessment of lower extremity performance and MET training program early after surgery. The patient made improvements in all functional tests and more importantly maintained a fairly equal distribution of body weight over both limbs during functional activities.

Isokinetic strength testing of minimally invasive total knee arthroplasty recovery

Fifty patients underwent isokinetic muscle strength testing before surgery and at 6 weeks, 3 months, 6 months, and 1 year after unilateral total knee arthroplasty using the minisubvastus surgical technique. Quadriceps muscle strength returned to preoperative levels by 3 months postoperatively and was 17% stronger at 6 months and 30% stronger at 1 year than preoperative levels (P < .05). At 1 year, the quadriceps strength of the involved knee was equivalent to that of the uninvolved knee (P = .81). When the entire study population was subdivided by age, weight, sex, and the presence of arthritis in the uninvolved knee, each subgroup still had equivalent quadriceps strength between the involved and uninvolved knees. This prospective study demonstrated that the minisubvastus total knee arthroplasty technique led to a more rapid and more complete recovery of muscle strength than has been previously demonstrated after total knee arthroplasty with a medial parapatellar arthrotomy.

Asymmetry in quadriceps rate of force development as a functional outcome measure in TKA

Quadriceps muscle strength is an important predictor of functional abilities in patients having TKA. However, because several daily activities are characterized by a limited time to generate force, it has been suggested that rate of force development (RFD) could better predict functional difficulties than maximal strength. We therefore hypothesized the side-to-side asymmetry would be larger for RFD than for maximal strength, and RFD asymmetry relates to subjective symptoms and/or functional daily living activities. We studied 31 subjects (17 women, 14 men) 6 +/- 1 months after undergoing TKA for unilateral osteoarthritis. Symptoms and limitations during activities of daily living were quantified using the knee outcome survey-activities of daily living scale (KOS-ADLS). Quadriceps maximal strength and RFD at different times (50 to 200 ms from contraction onset) were quantified during unilateral maximal voluntary isometric actions. Side-to-side asymmetries (involved versus uninvolved side) were larger for RFD (approximately 36%) than for maximal strength (approximately 24%). Subjective knee function related to all RFD asymmetry variables, but not to maximal strength asymmetry. In addition to maximal strength, quadriceps RFD in the first 100 to 200 ms from contraction onset provides an alternative functional outcome measure for individuals undergoing TKA.

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

BACKGROUND

Knee joint arthritis causes pain, decreased range of motion, and mobility limitation. Knee replacement reduces pain effectively. However, people with knee replacement have decreases in muscle strength ("force-generating capacity") of the involved leg and difficulties with walking and other physical activities.

OBJECTIVE AND DESIGN

The aim of this cross-sectional study was to determine the extent of deficits in knee extensor and flexor muscle torque and power (ability to perform work over time) and in the extensor muscle cross-sectional area (CSA) after knee joint replacement. In addition, the association of lower-leg muscle deficits with mobility limitations was investigated.

METHODS

Participants were 29 women and 19 men who were 55 to 75 years old and had undergone unilateral knee replacement surgery an average of 10 months earlier. The maximal torque and power of the knee extensor and flexor muscles were measured with an isokinetic dynamometer. The knee extensor muscle CSA was measured with computed tomography. The symmetry deficit between the knee that underwent replacement surgery ("operated knee") and the knee that did not undergo replacement surgery ("nonoperated knee") was calculated. Maximal walking speed and stair-ascending and stair-descending times were assessed.

RESULTS

The mean deficits in knee extensor and flexor muscle torque and power were between 13% and 27%, and the mean deficit in the extensor muscle CSA was 14%. A larger deficit in knee extension power predicted slower stair-ascending and stair-descending times. This relationship remained unchanged when the power of the nonoperated side and the potential confounding factors were taken into account.

LIMITATIONS

The study sample consisted of people who were relatively healthy and mobile. Some participants had osteoarthritis in the nonoperated knee.

CONCLUSIONS

Deficits in muscle torque and power and in the extensor muscle CSA were present 10 months after knee replacement, potentially causing limitations in negotiating stairs. To prevent mobility limitations and disability, deficits in lower-limb power should be considered during rehabilitation after knee replacement.

Reversing muscle and mobility deficits 1 to 4 years after TKA: a pilot study

Muscle and mobility deficits can persist for years after a total knee arthroplasty (TKA). The purposes of this study were (1) to determine if 12 weeks of rehabilitation with resistance exercise induces increases in muscle size, strength, and mobility in individuals 1 to 4 years after a TKA; and (2) to compare the muscle and mobility outcomes of a traditional resistance exercise rehabilitation program with a rehabilitation program focused on eccentric resistance exercise. Seventeen individuals (13 women, four men; mean age, 68 years; age range, 55-80 years) with either a unilateral or bilateral TKA (total of 24 knees) were included in this matched and randomized repeated-measures rehabilitation pilot trial. Increases in quadriceps muscle volume and knee extension strength followed 12 weeks of eccentric exercise. Improvements were also noted in four mobility tests. Similar improvements were noted in the traditional group in two mobility tests. An increase in muscle size and strength and an improvement in levels of mobility can occur after 12 weeks of resistance exercise in older individuals 1 to 4 years after TKA. When the exercise mode focuses on eccentric resistance, the muscle growth response is greater as is the improvement in important mobility tasks.

LEVEL OF EVIDENCE

Level II, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Avaliação isocinética em pacientes submetidos à artroplastia total de joelho

OBJETIVOS: Tem-se afirmado que a via de acesso minimamente invasiva na artroplastia total de joelho (ATJ) por não agredir o músculo quadríceps femoral permite reabilitação mais precoce. A fim de verificar a influência da preservação do aparelho extensor no ato cirúrgico, avaliou-se a força da musculatura extensora e flexora do joelho em pacientes submetidos à ATJ por duas vias de acesso diferentes. MATERIAIS E MÉTODOS: Este estudo comparou, no período de janeiro de 2005 a julho de 2006, os valores de torque máximo e de trabalho total obtidos por dinamometria isocinética aos seis meses de pós-operatório. Foram avaliados 12 indivíduos submetidos a ATJ por via de acesso minimamente invasiva e 8 indivíduos submetidos a ATJ por via de acesso transquadricipital. RESULTADOS: A análise estatística dos valores de torque máximo e de trabalho total absolutos e corrigidos pelo peso corporal não demonstrou diferença entre os dois grupos. CONCLUSÃO: Não há diferença de força da musculatura extensora e flexora do joelho aos seis meses de cirurgia.

Total knee arthroplasty: muscle impairments, functional limitations, and recommended rehabilitation approaches

The number of total knee arthroplasty (TKA) surgeries performed each year is predicted to steadily increase. Following TKA surgery, self-reported pain and function improve, though individuals are often plagued with quadriceps muscle impairments and functional limitations. Postoperative rehabilitation approaches either are not incorporated or incompletely address the muscular and functional deficits that persist following surgery. While the reason for quadriceps weakness is not well understood in this patient population, it has been suggested that a combination of muscle atrophy and neuromuscular activation deficits contribute to residual strength impairments. Failure to adequately address the chronic muscle impairments has the potential to limit the long-term functional gains that may be possible following TKA. Postoperative rehabilitation addressing quadriceps strength should mitigate these impairments and ultimately result in improved functional outcomes. The purpose of this paper is to describe these quadriceps muscle impairments and discuss how these impairments can contribute to the related functional limitations following TKA. We will also describe the current concepts in TKA rehabilitation and provide recommendations and clinical guidelines based on the current available evidence.

LEVEL OF EVIDENCE

Therapy, level 5.

Altérations architecturales et neuromusculaires du muscle vastus lateralis chez des patients âgés atteints de gonarthrose unilatérale

AIM

The aim of this study was to determine the mechanisms involved in muscle weakness in elderly patients with unilateral knee osteoarthritis.

SUBJECTS

We investigated 7 patients with unilateral knee osteoarthritis.

METHOD

We measured knee position sense and isometric maximal voluntary contraction (MVC) of the knee extensors. Electromyographic (EMG) measurement of biceps femoris (BF), rectus femoris (RF), vastus lateralis (VL) and vastus medialis (VM) involved different levels of contraction (25, 50, 75 and 100% MVC). Neuromuscular efficiency of quadriceps was also calculated (MVC/EMG). Ultrasonography was used to investigate the VL architectural parameters at the median part of the VL for different levels of contraction (25, 50, and 75% MVC). All tests were performed on the osteoarthritic and healthy knees.

RESULTS

The quadriceps MVC of the affected knee was reduced by 30%. The VL thickness of the affected knee was 10% smaller than that of the unaffected knee. VL activity seen on EMG did not differ between knees, but RF, VM and BF activity was greater in the unaffected than affected knee. Neuromuscular efficiency was higher (26%) in the unaffected knee. Knee position sense was reduced by 33% in the affected knee.

CONCLUSION

Quadriceps weakness associated with knee osteoarthritis seems to be related to changes in muscle rather than pennation angle and changes in fascicule length.

Early neuromuscular electrical stimulation to optimize quadriceps muscle function following total knee arthroplasty: a case report

STUDY DESIGN

Case report.

BACKGROUND

Following total knee arthroplasty (TKA), restoration of normal quadriceps muscle function is rare. One month after surgery, quadriceps torque (force) is only 40% of preoperative values and quadriceps activation is only 82% of preoperative levels, despite initiating postoperative rehabilitation the day after surgery. Early application of neuromuscular electrical stimulation (NMES) offers a possible approach to minimize loss of quadriceps torque more effectively than traditional rehabilitation exercises alone.

CASE DESCRIPTION

A 65-year-old female underwent a right, cemented TKA. Isometric quadriceps and hamstrings muscle torque were measured preoperatively and at 3, 6, and 12 weeks after TKA. Quadriceps muscle activation was measured using a doublet interpolation technique at the same time points. The patient participated in a traditional TKA rehabilitation program augmented by NMES, which was initiated 48 hours after surgery and continued twice a day for the first 3 weeks, and once daily for 3 additional weeks.

OUTCOMES

Preoperatively, the involved quadriceps produced 75% of the torque of the uninvolved side and demonstrated only 72.9% activation. At 3, 6, and 12 weeks after TKA, quadriceps torque was greater than the preoperative values of the involved side by 16%, 29%, and 56%, respectively. Similarly, activation improved to 93.4%, 94.6%, and 93.5% at 3, 6, and 12 weeks after TKA.

DISCUSSION

Mitigating quadriceps muscle weakness immediately after TKA using early NMES may improve functional outcomes, because quadriceps weakness has been associated with numerous functional limitations and an increased risk for falls. Despite presenting preoperatively with substantial quadriceps torque and activation deficits, the patient in this case demonstrated improvements in quadriceps function at all the times measured, all of which were superior to those reported in the literature. The patient also made substantial improvements in functional outcomes, including the Knee Injury and Osteoarthritis Outcome Score (KOOS), 6-minute walk test, timed up and go (TUG) test, stair-climbing test, and the SF-36 Physical Component Score. Appropriately controlled clinical trials will be necessary to determine whether such favorable outcomes following TKA are specifically attributable to the addition of NMES to the rehabilitation program.