Quadriceps strength and volitional activation before and after total knee arthroplasty for osteoarthritis.

INTRODUCTION: Patients with osteoarthritis (OA) of the knee have quadriceps weakness and arthrogenous muscle inhibition (AMI). While total knee arthroplasty (TKA) reliably reduces pain and improves function in patients with knee OA, quadriceps weakness persists after surgery. The purpose of this investigation was to assess contributions of AMI to quadriceps weakness before and after TKA and to assess the effect of pain on AMI. METHODS: Twenty-eight patients with unilateral, end-stage, primary knee OA were tested an average of 10 days before and 26 days after TKA. The mean age at time of operation was 63 years (range 49-82 years). Measurements on the involved and uninvolved knees were performed using the burst-superimposition technique, where supramaximal electrical stimulation is superimposed on a voluntary contraction. Knee pain during contraction was measured using a numeric rating scale. RESULTS: The involved quadriceps were significantly weaker than the uninvolved prior to TKA (p<0.05). Quadriceps strength decreased by 60% (p<0.001) and activation decreased 17% (p<0.001) after TKA. Changes in muscle activation accounted for 65% of the variability in the change in quadriceps strength (r(2)=0.65) (p<0.001). Knee pain during muscle contraction accounted for a small, but significant portion of the change in voluntary activation (r(2)=0.22) (p=0.006). DISCUSSION: Exercise regimens that emphasize strong muscle contraction and clinical tools that facilitate muscle activation like biofeedback and neuromuscular electrical stimulation may be necessary to reverse the quadriceps activation failure and weakness in the patients with knee OA that worsens after TKA. The failure of current rehabilitation regimens to directly address activation deficits within the first months after surgery may explain the persistent quadriceps weakness in patients after TKA.     

The use of neuromuscular electrical stimulation to improve activation deficits in a patient with chronic quadriceps strength impairments following total knee arthroplasty

STUDY DESIGN: Case report. BACKGROUND: Long-term deficits in quadriceps femoris muscle strength and impaired muscle activation are common among individuals with total knee arthroplasty (TKA). Failure to address strength-related impairments results in poor surgical and functional outcomes, which may accelerate the progression of osteoarthritis in other lower extremity joints. The purpose of the current case report was to implement a neuromuscular electrical stimulation (NMES) treatment protocol in conjunction with an intense weight-training program, with the aim of reversing persistent quadriceps muscle impairments after TKA. CASE DESCRIPTION: The patient was a 62-year-old male cyclist 12 months following simultaneous, bilateral TKA with impairments in left quadriceps strength and volitional muscle activation. His left quadriceps strength was 26% weaker than his right and central activation ratio (CAR) of his left quadriceps was 13% lower than his right quadriceps CAR. NMES to the left quadriceps was implemented for 6 weeks, in addition to an intense volitional weight-training program with emphasis on unilateral lower extremity exercises. OUTCOMES: The patient demonstrated a 25% improvement in left quadriceps femoris maximal volitional force output following 16 treatments of combined NMES and volitional strength training over a 6-week period. The patient's volitional muscle activation improved from a CAR of 0.83 before treatment to 0.97 after treatment. At discharge from physical therapy and at his 18-month postoperative follow-up, the patient's left quadriceps strength was only 4% lower than his right quadriceps strength. At the 24-month follow-up, the patient's left quadriceps strength was 6% stronger than his right quadriceps strength. DISCUSSION: The patient was able to achieve symmetrical quadriceps strength and complete muscle activation following 6 weeks of NMES and volitional strength training. An intense strengthening program may have the potential to reverse persistent strength-related impairments following TKA.     

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.     

Strength and voluntary activation of quadriceps femoris muscle in total knee arthroplasty with midvastus and subvastus approaches

To determine and compare the influence of 2 different approaches on quadriceps femoris muscle function in total knee arthroplasty (TKA), 20 patients (14 women, 6 men) with bilateral knee osteoarthritis underwent a 1-stage bilateral TKA. Surgical approaches (subvastus, midvastus) were performed by a random selection. Measurements of quadriceps voluntary activation and maximal voluntary contraction were estimated by a twitch interpolation technique before, 3 and 6 months after TKA. Knee pain was quantified by the Lewis Score. There was no difference between the 2 approaches at 3 and 6 months after TKA with regard to maximal voluntary contraction (P = 0.84, F = 0.041) and voluntary activation (P = .863, F = 0.031). In the subvastus group was a significantly higher knee pain until 6 months after surgery (P = .02). The subvastus approach for TKA does not provide any advantages compared with the midvastus approach with respect to the quadriceps femoris muscle strength in the early postoperative period. Furthermore, the subvastus approach caused significantly more pain postoperatively.     

Quadriceps muscle function after high tibial osteotomy for osteoarthritis of the knee

In patients with osteoarthritis of the knees, quadriceps muscle dysfunction is an early and common clinical feature and an important determinant of disability. In the current study, changes in quadriceps muscle strength and voluntary quadriceps muscle activation after high tibial osteotomies for primary osteoarthritis of the knee in 19 patients were investigated. Quadriceps muscle function was assessed during different degrees of isometric maximum voluntary contraction using a specially built chair. One year after surgery all patients had reexamination of their surgically treated and contralateral knees. Voluntary activation and maximum voluntary contraction values of the followup assessment were significantly lower in the surgically treated knees compared with the preoperative assessment. In the contralateral knees, there were no differences between preoperative and followup measurements. High tibial osteotomy is an extraarticular operative therapeutic approach to treatment of osteoarthritis of the knee that does not lead to improvement of quadriceps muscle function. Because there is evidence that quadriceps sensorimotor dysfunction is important not only for the disability in osteoarthritis of the knee, but also for progression of the disease, knee function may be worsened by high tibial osteotomy in some patients.     

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

We studied 30 patients with arthrosis in one knee operated on with a cemented (n 26) or an uncemented total knee arthroplasty (TKA) (n 4). Full weight-bearing from the first postoperative day was allowed in all patients, and they received standard postoperative physiotherapy. 1 week prior to surgery, and after 3 and 6 months, isokinetic and isometric muscle strength in both legs were measured, using a Cybex 6000 dynamometer. Isokinetic tests showed a bilateral, significant, and progressive increase (30-53%) in flexor muscle strength most pronounced in the operated legs. Isokinetic extensor strength increased significantly (14-18%) in the operated legs, while in the contralateral legs, a limited increase was found. Isometric flexion strength significantly decreased in the operated knees (17%). Isometric extension strength showed a temporary decrease at 3 months, which returned to the preoperative level. No significant change in isometric strength was observed in the contralateral legs. The knee pain during the muscle strength measurements decreased significantly from the preoperative level, which may indicate that the substantial pain relief within 3 months after a TKA is an important factor for evaluation of muscle strength.     

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

We studied 30 patients with arthrosis in one knee operated on with a cemented (n 26) or an uncement-ed total knee arthroplasty (TKA) (n 4). Full weight-bearing from the first postoperative day was allowed in all patients, and they received standard postoperative physiotherapy. 1 week prior to surgery, and after 3 and 6 months, isokinetic and isometric muscle strength in both legs were measured, using a Cybex 6000 dynamometer. Isokinetic tests showed a bilateral, significant, and progressive increase (30-53%) in flexor muscle strength most pronounced in the operated legs. Isokinetic extensor strength increased significantly (14-18%) in the operated legs, while in the contralateral legs, a limited increase was found. Isometric flexion strength significantly decreased in the operated knees (17%).

Isometric extension strength showed a temporary decrease at 3 months, which returned to the preoperative level. No significant change in isometric strength was observed in the contralateral legs. The knee pain during the muscle strength measurements decreased significantly from the preoperative level, which may indicate that the substantial pain relief within 3 months after a TKA is an important factor for evaluation of muscle strength.     

Home based neuromuscular electrical stimulation as a new rehabilitative strategy for severely disabled patients with chronic obstructive pulmonary disease (COPD)

BACKGROUND: Passive training of specific locomotor muscle groups by means of neuromuscular electrical stimulation (NMES) might be better tolerated than whole body exercise in patients with severe chronic obstructive pulmonary disease (COPD). It was hypothesised that this novel strategy would be particularly effective in improving functional impairment and the consequent disability which characterises patients with end stage COPD. METHODS: Fifteen patients with advanced COPD (nine men) were randomly assigned to either a home based 6 week quadriceps femoris NMES training programme (group 1, n=9, FEV(1)=38.0 (9.6)% of predicted) or a 6 week control period before receiving NMES (group 2, n=6, FEV(1)=39.5 (13.3)% of predicted). Knee extensor strength and endurance, whole body exercise capacity, and health related quality of life (Chronic Respiratory Disease Questionnaire, CRDQ) were assessed. RESULTS: All patients were able to complete the NMES training programme successfully, even in the presence of exacerbations (n=4). Training was associated with significant improvements in muscle function, maximal and endurance exercise tolerance, and the dyspnoea domain of the CRDQ (p<0.05). Improvements in muscle performance and exercise capacity after NMES correlated well with a reduction in perception of leg effort corrected for exercise intensity (p<0.01). CONCLUSIONS: For severely disabled COPD patients with incapacitating dyspnoea, short term electrical stimulation of selected lower limb muscles involved in ambulation can improve muscle strength and endurance, whole body exercise tolerance, and breathlessness during activities of daily living.     

Does Blood Flow Restriction Therapy Improve Leg Strength in Patients With a Painful Total Knee Arthroplasty?

BackgroundBlood flow restriction (BFR) therapy has been proposed to help patients build strength with fewer repetitions than standard physical therapy (PT). We sought to determine if BFR would improve quadriceps and hamstring strength in patients with instability and perceived weakness >1 year after primary total knee arthroplasty (TKA).MethodsWe retrospectively reviewed 48 patients with painful TKAs and flexion instability as well as quadriceps and hamstring weakness who performed a 6-week PT program and received isokinetic strength measurements (ISMs). Thirty-six patients completed a standard PT program (non-BFR) and 12 patients completed a BFR regimen. ISMs were taken before and after PT to quantify quadriceps and hamstring power, torque, and work compared to the contralateral leg. Statistical analysis was conducted on pre-PT and post-PT ISMs and decisions for revision surgery.ResultsThere were no differences in ISMs after PT between the BFR and non-BFR groups. The non-BFR group showed statistically significant strength improvements in flexion but not extension (+28.7%-32.8%, P = .0145-.255). Although no significant difference was found in the BFR group, they saw improvements in all extension strength metrics (19.4%-23.4%, P = .3315-.3901) and flexion (25.7%-29.9%, P = .1994-.2392). No difference was observed between the groups in the rates of subsequent revision TKA (8.3% vs 16.7%, P = .3362).ConclusionBFR did not improve quadriceps and hamstring strength compared to PT alone in patients with instability and weakness after TKA. Over 80% of total patients chose to avoid revision TKA after completion of focused PT with or without BFR.     

Early quadriceps strength loss after total knee arthroplasty. The contributions of muscle atrophy and failure of voluntary muscle activation

BACKGROUND: While total knee arthroplasty reduces pain and provides a functional range of motion of the knee, quadriceps weakness and reduced functional capacity typically are still present one year after surgery. The purpose of the present investigation was to determine the role of failure of voluntary muscle activation and muscle atrophy in the early loss of quadriceps strength after surgery. METHODS: Twenty patients with unilateral knee osteoarthritis were tested an average of ten days before and twenty-seven days after primary total knee arthroplasty. Quadriceps strength and voluntary muscle activation were measured with use of a burst-superimposition technique in which a supramaximal burst of electrical stimulation is superimposed on a maximum voluntary isometric contraction. Maximal quadriceps cross-sectional area was assessed with use of magnetic resonance imaging. RESULTS: Postoperatively, quadriceps strength was decreased by 62%, voluntary activation was decreased by 17%, and maximal cross-sectional area was decreased by 10% in comparison with the preoperative values; these differences were significant (p < 0.01). Collectively, failure of voluntary muscle activation and atrophy explained 85% of the loss of quadriceps strength (p < 0.001). Multiple linear regression analysis revealed that failure of voluntary activation contributed nearly twice as much as atrophy did to the loss of quadriceps strength. The severity of knee pain with muscle contraction did not change significantly compared with the preoperative level (p = 0.31). Changes in knee pain during strength-testing did not account for a significant amount of the change in voluntary activation (p = 0.14). CONCLUSIONS: Patients who are managed with total knee arthroplasty have profound impairment of quadriceps strength one month after surgery. This impairment is predominantly due to failure of voluntary muscle activation, and it is also influenced, to a lesser degree, by muscle atrophy. Knee pain with muscle contraction played a surprisingly small role in the reduction of muscle activation.     

Strength response in human femoris muscle during 2 neuromuscular electrical stimulation programs

STUDY DESIGN: Experimental mixed repeated-measures design. OBJECTIVE: To determine the effect of 2 versus 3 neuromuscular electrical stimulation (NMES) training sessions per week on the response to strength training of the quadriceps femoris muscle. BACKGROUND: Many studies have examined the influence of training intensity (percent maximal voluntary isometric contraction [MVIC]) during NMES on the strength response of the quadriceps femoris muscle. However, no study has examined the effects of the number of NMES sessions per week on the change in strength of the quadriceps femoris. METHODS AND MEASURES: Twenty-seven healthy subjects (mean age +/- SD, 23.2 +/- 3.2 years) volunteered for the study and were randomly assigned to 1 of 3 groups; control group (no electrical stimulation); group 2 (NMES 2 times per week); and group 3 (NMES 3 times per week). Groups 2 and 3 received NMES (10 minutes per session) over a 4-week period for a total of 8 and 12 NMES training sessions, respectively. The isometric quadriceps femoris muscle force produced during NMES was monitored during each treatment minute. The MVIC force of the quadriceps femoris was assessed prior to the first week and at the start of weeks 2, 3, and 4 of the 4-week training program, with a final measurement after the fourth week (5 total measurements) for all subjects. RESULTS: Only the mean percent change in quadriceps MVIC before and after the 4 weeks of training with NMES between the control group and group 3 was significantly different (P = .021). CONCLUSIONS: Based on the electrical stimulation parameters and healthy subjects used in this study, NMES caused significant increases in the quadriceps femoris muscle strength when used for 3 training sessions per week for 4 weeks. It is possible that the use of a different electrical stimulation paradigm and/or a different patient population may result in strength gains with 1 or 2 sessions per week.     

Factors explaining chronic knee extensor strength deficits after ACL reconstruction

Persistent quadriceps muscle weakness is common after anterior cruciate ligament (ACL) reconstruction. The mechanisms underlying these chronic strength deficits are not clear. This study examined quadriceps strength in people 2–15 years post‐ACL reconstruction and tested the hypothesis that chronic quadriceps weakness is related to levels of voluntary quadriceps muscle activation, antagonistic hamstrings moment, and peripheral changes in muscle. Knee extensor strength and activation were evaluated in 15 ACL reconstructed and 15 matched uninjured control subjects using an interpolated triplet technique. Electrically evoked contractile properties were used to evaluate peripheral adaptations in the quadriceps muscle. Antagonistic hamstrings moments were predicted using a practical mathematical model. Knee extensor strength and evoked torque at rest were significantly lower in the reconstructed legs (p < 0.05). Voluntary activation and antagonistic hamstrings activity were similar across legs and between groups (p > 0.05). Regression analyses indicated that side‐to‐side differences in evoked torque at rest explained 71% of the knee extensor strength differences by side (p < 0.001). Voluntary activation and antagonistic hamstrings moment did not contribute significantly (p > 0.05). Chronic quadriceps weakness in this sample was primarily related to peripheral changes in the quadriceps muscle, not to levels of voluntary activation or antagonistic hamstrings activity. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:633–640, 2011     

Quadriceps femoris muscle weakness and activation failure in patients with symptomatic knee osteoarthritis.

PURPOSE: Quadriceps weakness is common in patients with knee osteoarthritis (OA), and has been attributed to failure of voluntary activation. Methodological differences may have contributed to previous reports of extensive failure of voluntary activation in patients with osteoarthritis. The purpose of this study was to determine the extent of quadriceps muscle weakness and activation failure in middle aged patients with symptomatic medial knee osteoarthritis using maximum voluntary isometric contractions (MVIC) and a burst superimposition technique. METHODS: Measurements of quadriceps MVIC and extent of voluntary activation were made in 12 subjects with knee OA and 12 similarly aged uninjured subjects. Voluntary activation was tested by superimposing a train of electrical stimulation on a maximal effort volitional contraction of the quadriceps muscle. RESULTS: The group of subjects with knee OA had significantly less quadriceps strength relative to body mass index (BMI) than the group of control subjects (p=0.010). No difference in voluntary activation was observed (p=0.233), however, 50% of the OA group, and only 25% of the control group failed to fully activate the quadriceps. DISCUSSION: The finding of quadriceps weakness is consistent with past literature. Providing adequate instruction, feedback, and several attempts to maximally contract the muscle likely yielded greater volitional activation (thus less activation failure) than had been reported previously. This finding has implications for the rehabilitation of weakened quadriceps in patients with knee osteoarthritis.     

Neuromuscular quadriceps dysfunction prior to osteoarthritis of the knee.

Decreased maximal quadriceps strength and voluntary activation has been observed in patients with osteoarthritis in previous studies, but those results do not allow any conclusions to be drawn as to whether quadriceps dysfunction precedes or follows osteoarthritis. Thirty-two patients (group a) who underwent partial meniscectomy 48+/-9 month prior to the study were matched according to their weight and body mass index with a control group (group b). The twitch interpolation technique was used to determine maximal voluntary contraction (MVC) and voluntary activation (VA) of the quadriceps muscle of both legs. Subjective assessment of the knee was performed using the Lysholm-Score. AP and lateral X-rays of the operated knee were obtained. None of the participants showed any evidence of characteristic radiological or clinical signs for osteoarthritis. A significantly lower MVC was noticed in both the affected and the contralateral knee of group a in comparison to group b (p < 0.01). The VA in group a yielded 80.9+/-15.4% for the injured side and 83.1+/-11.5% for the contralateral side, with no statistical difference (p = 0.18). The VA in group b was 89.4+/-5.8% for the right side and 88+/-6.8% for the left side both being significantly higher in comparison to group a. This study has shown, that patients following meniscus resection present with bilateral quadriceps weakness as already described in patients with manifest osteoarthritis. The authors hypothesise that muscle dysfunction may be an etiologic factor underlying the pathologic changes of osteoarthritis. Whether muscle dysfunction occurs also at other sites, e.g. in the upper extremity, remains unclear but would be of interest in order to detect a generalized neuromuscular dysfunction.     

Neuromuscular electrical stimulation (NMES) reduces structural and functional losses of quadriceps muscle and improves health status in patients with knee osteoarthritis

Knee osteoarthritis (OA) is associated with quadriceps atrophy and weakness, so muscle strengthening is an important point in the rehabilitation process. Since pain and joint stiffness make it often difficult to use conventional strength exercises, neuromuscular electrical stimulation (NMES) may be an alternative approach for these patients. This study was aimed at (1) identifying the associations of knee OA with quadriceps muscle architecture and strength, and (2) quantifying the effects of a NMES training program on these parameters. In phase 1, 20 women with knee OA were compared with 10 healthy female, asymptomatic, age‐matched control subjects. In phase 2, 12 OA patients performed an 8‐week NMES strength training program. OA patients presented smaller vastus lateralis thickness (11.9 mm) and fascicle length (20.5%) than healthy subjects (14.1 mm; 24.5%), and also had a 23% smaller knee extensor torque compared to the control group. NMES training increased vastus lateralis thickness (from 12.6 to 14.2 mm) and fascicle length (from 19.6% to 24.6%). Additionally, NMES training increased the knee extensor torque by 8% and reduced joint pain, stiffness, and functional limitation. In conclusion, OA patients have decreased strength, muscle thickness, and fascicle length in the knee extensor musculature compared to control subjects. NMES training appears to offset the changes in quadriceps structure and function, as well as improve the health status in patients with knee OA. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 511–516, 2013     

Evaluation of quadriceps strength and voluntary activation after unicompartmental arthroplasty for medial osteoarthritis of the knee.

INTRODUCTION: In early and moderate stages of osteoarthritis (OA) of the knee, arthrogenous muscle inhibition (AMI) is an important factor for the initiation and the progression of the disease. Although AMI has been shown to be reduced after physiotherapeutical exercises resulting in significant improvements in disability, implantation of unicondylar knee arthroplasties is much provided in these stages of OA. Therefore, in the present study we investigate changes in quadriceps muscle after implantation of such prostheses as compared to physiotherapeutical treatment, alone. METHODS: In eighteen patients with bilateral moderate knee OA, who were treated with unicondylar knee arthroplasty we investigated voluntary activation (VA) and maximum voluntary contraction (MVC) of the quadriceps femoris muscle. There were 7 males and 11 females, the mean age at time of operation was 67 years (range 58-76 years). Measurements on both sides were performed preoperatively and 18 months postoperatively using the twitch-interpolation technique. RESULTS: Follow-up assessment revealed a significant VA and MVC increase in both the surgically treated knees and in the contralateral knees treated by physiotherapy alone. However, VA and MVC improvements were significantly higher in the operated on knees than in those treated by physiotherapy alone. DISCUSSION: Both physiotherapeutical exercise and unicondylar knee replacements lead to an improvement of quadriceps motor function in knee OA. The greater improvement in knees with both knee replacement and physiotherapy might be related to the intraoperative removal of arthritic tissue in these knees.     

Altered loading during walking and sit-to-stand is affected by quadriceps weakness after total knee arthroplasty.

PURPOSE: Total knee arthroplasty (TKA) successfully reduces pain, but has not achieved comparable improvements in function. We hypothesized that quadriceps strength affects performance by altering loading and movement patterns during functional tasks. METHODS: Fourteen subjects with isolated, unilateral TKA were tested three months after surgery. Quadriceps strength was assessed isometrically and kinematics, kinetics, and EMG were collected during level walking and sit-to-stand (STS). Function was assessed using the timed up and go test (TUG), stair climbing test (SCT), and the 6 min walk test (6MW). RESULTS: Functional performance was significantly related to the quadriceps strength of both legs, but was more strongly related to the uninvolved strength (involved rho=-0.43 with TUG; -0.65 with SCT; 0.64 with 6MW) (uninvolved rho=-0.63 with TUG; -0.68 with SCT; 0.77 with 6MW). During STS, subjects shifted weight away from the operated limb (p<0.01). Quadriceps muscle activity and the extension moments at the knee and hip were smaller in the involved compared to the uninvolved (p<0.05). The amount of asymmetry in knee excursion during weight acceptance in gait, the asymmetry in weight bearing from sit-to-stand, and the uninvolved hip extension moment during STS were related to the amount of asymmetry in quadriceps strength (rho>0.56, p<0.05). CONCLUSIONS: Quadriceps weakness in patients with TKA has a substantial impact on the movement patterns and performance of the knee during functionally important tasks.     

Effects of home-based resistance training and neuromuscular electrical stimulation in knee osteoarthritis: a randomized controlled trial

ABSTRACT: BACKGROUND: Quadriceps femoris muscle (QFM) weakness is a feature of knee osteoarthritis (OA) and exercise programs that strengthen this muscle group can improve function, disability and pain. Traditional supervised resistance exercise is however resource intensive and dependent on good adherence which can be challenging to achieve in patients with significant knee OA. Because of the limitations of traditional exercise programs, interest has been shown in the use of neuromuscular electrical stimulation (NMES) to strengthen the QFM. We conducted a single-blind, prospective randomized controlled study to compare the effects of home-based resistance training (RT) and NMES on patients with moderate to severe knee OA. METHODS: 41 patients aged 55 to 75 years were randomised to 6 week programs of RT, NMES or a control group receiving standard care. The primary outcome was functional capacity measured using a walk test, stair climb test and chair rise test. Additional outcomes were self-reported disability, quadriceps strength and cross-sectional area. Outcomes were assessed pre- and post-intervention and at 6 weeks post-intervention (weeks 1, 8 and 14 respectively). RESULTS: There were similar, significant improvements in functional capacity for the RT and NMES groups at week 8 compared to week 1 (p<0.001) and compared to the control group (p<0.005), and the improvements were maintained at week 14 (p<0.001). Cross sectional area of the QFM increased in both training groups (NMES: +5.4%; RT: +4.3%; p=0.404). Adherence was 91% and 83% in the NMES and RT groups respectively (p=0.324). CONCLUSIONS: Home-based NMES is an acceptable alternative to exercise therapy in the management of knee OA, producing similar improvements in functional capacity. Trial registration: Current Controlled Trials ISRCTN85231954.     

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

BackgroundThere 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.MethodsThis 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.ResultsPatients 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).ConclusionPatients 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 evidenceIV (Case series).     

Does Patient Perception Differ Following Adductor Canal Block and Femoral Nerve Block in Total Knee Arthroplasty? A Simultaneous Bilateral Randomized Study

Background

Femoral nerve block (FNB) has been used as part of the multimodal analgesia after total knee arthroplasty (TKA), but leads to weakness in the quadriceps muscles. Recently, adductor canal block (ACB) was reported to provide effective pain relief while sparing the strength of the quadriceps. This simultaneous bilateral randomized study investigated whether patients perceived differences between ACB and the FNB after same-day bilateral TKA.