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.     

Strength and voluntary activation of the quadriceps femoris muscle at different severities of osteoarthritic knee joint damage.

OBJECTIVE: Improvements of quadriceps motor deficits represent a major therapeutical target in knee osteoarthritis (OA). In the present study, we investigated changes in quadriceps function at different stages of osteoarthritic cartilage damage. METHODS: Measurements of quadriceps voluntary activation (VA) and maximum voluntary contraction (MVC) were performed by a twitch interpolation technique and the total muscular capacity (TMC) was calculated as the ratio of MVC and VA. We assessed 68 patients (56.7+/-9.5 years) with stage II and 154 patients (65.6+/-6.0 years) with stage IV chondropathy. As controls, we used 85 age related healthy subjects (58.1+/-8.7 years). RESULTS: While TMC was significantly lower in stage IV (90.6+/-43.7 Nm) than in stage II chondropathy (109.6+/-51.0) there were no differences in the MVCs between both groups. Quadriceps VA was even higher in stage IV (77.2+/-13.2%) than in stage II chondropathy (70.8+/-16.0%). In the controls, MVC, VA and TMC were significantly higher than in both OA groups. CONCLUSION: We assume that a decrease of TMC might occur within the course of OA and, in consequence, VA increases to maintain quadriceps MVC.     

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.     

Bilateraler Funktionsverlust der Quadrizepsmuskulatur nach einseitiger Kreuzbandruptur mit Begleitverletzung durch zentrales Aktivierungsdefizit

The aim of the study was to investigate the ability to activate the quadriceps femoris muscle voluntarily in patients after severe knee injuries and it's influence on muscle function. 33 male patients after ACL-rupture with concomitant injuries were investigated with a twitch-interpolation-method to determine the maximal voluntary contraction force (MVC) and the ability to activate the quadriceps muscle voluntarily. The results were compared to a previously investigated group of patients after isolated ACL-rupture and to an aged-matched control group. The patients with extensive knee injuries presented a significant higher deficit of voluntary quadriceps muscle activation on the injured (78.8 +/- 2.09%, mean +/- SEM) and equally on the uninjured side (78.9 +/- 1.91%) compared to the patients after isolated ACL-rupture and to controls. A minor MVC-deficit of the patients quadriceps muscle of the uninjured side could be explained by the voluntary activation deficit alone, the major MVC deficit of the injured side by muscle atrophy and a voluntary activation deficit. The activation deficit is probably the underlying reason for persisting muscle wasting and [not readable: see text]     

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.     

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.     

Effects of reconstruction of the anterior cruciate ligament on voluntary activation of quadriceps femoris a prospective twitch interpolation study.

The loss of full muscle activation contributes to weakness of the quadriceps muscle in patients with deficiency of the anterior cruciate ligament (ACL). We examined whether a deficit of voluntary activation (VA) of the quadriceps muscle can be reversed by reconstruction of the ACL and assessed its influence on muscle strength and clinical parameters. We evaluated 12 male subjects with an isolated tear of the ACL and 12 matched control subjects before operation and two years after reconstruction of the ACL. Assessment included measurements of isometric knee-extension torque at maximal voluntary contraction (MVC force), knee stability tests, the International Knee Ligament Standard Evaluation Form and the Tegner activity score. A sensitive method of twitch interpolation was used to quantify the VA and to calculate true muscle force. Before operation we found a deficit of VA on both the injured (mean +/- SEM 74.9 +/- 3.5%) and the uninjured side (74.6 +/- 3.0%) in comparison with the control group (91 +/- 0.9%). Two years after reconstruction of the ACL the VA improved significantly on both sides but remained less than that of the controls. Correlation analysis revealed an improvement of the VA in patients who returned to a higher level of activity. The deficit of true muscle force, however, persisted regardless of the clinical outcome and ligament stability.     

Neuromuscular electrical stimulation for quadriceps muscle strengthening after bilateral total knee arthroplasty: a case series

STUDY DESIGN: A case series. OBJECTIVES: The purpose of this case series was to assess the effect of high-intensity neuromuscular electrical stimulation (NMES) on quadriceps strength and voluntary activation following total knee arthroplasty (TKA). BACKGROUND: Following TKA, patients exhibit long-term weakness of the quadriceps and diminished functional capacity compared to age-matched healthy controls. The pain and swelling that results from surgery may contribute to quadriceps weakness. The use of high-intensity NMES has previously been shown to be effective in quickly restoring quadriceps strength in patients with weakness after surgery. METHODS AND MEASURES: All patients were treated for 6 weeks, 2 to 3 visits per week, in outpatient rehabilitation. Five patients (NMES group) participated in a voluntary exercise program for both knees and NMES for the weaker knee. Three patients (exercise group) participated in a voluntary exercise program for both knees without NMES. For each treatment session, 10 isometric electrically elicited muscle contractions were administered at maximally tolerated doses to the initially weaker leg of the NMES group. Quadriceps strength and muscle activation were repeatedly assessed up to 6 months after surgery using burst superimposition techniques. RESULTS: At 6 months, the weak NMES-treated legs of 4 of 5 patients in the NMES group had surpassed the strength of the contralateral leg. In contrast, none of the weak legs in the exercise group were stronger than the contralateral leg at 6 months. Changes in quadriceps muscle activation mirrored the changes exhibited in strength. CONCLUSION: When NMES was added to a voluntary exercise program, deficits in quadriceps muscle strength and activation resolved quickly after TKA.     

Therapeutic effect of high speed voluntary muscle contractions on muscle soreness and muscle performance

The purpose of this study was to examine the effects of a high velocity therapeutic exercise regimen (20 voluntary maximum knee extension/flexion contractions at approximately 300 degrees /sec, 3-min recovery repeated for 6-sets), on muscle soreness and muscular performance. Data was collected immediately prior to inducing muscle soreness with an eccentric stepping exercise (baseline), immediately after the muscle soreness exercise bout, at 24 hours (when intervention was initiated to the experimental group), and at 48 hours after the muscle soreness bout. Dependent variables measured for the ten subjects were: 1) Maximum voluntary contraction (MVC) by the quadriceps;2) Peak torque (PT) by the quadriceps at high resistance;3) Total work (TW) by the quadriceps at low resistance;4) Intensity (I) of muscle soreness of the quadriceps;5) Amount of quadriceps [Area-(A)] affected by muscle soreness;6) Soreness perception index (SPI) of quadriceps (IXA).MVC, PT, and TW percent decrease from baseline were significantly less (p < 0.05) for the experimental group than the control group at 48 hours postmuscle soreness bout (MVC: 8.3 versus 33.4%; PT: 3.8 versus 12.1%; TW: 2.3 versus 13.8%, respectively). SPI was also significantly less (p < 0.05) at 48 hours postmuscle soreness bout for the experimental versus control [0.8 (I = 0.027 x A = 29.3) versus 1.4 (I = 0.029 x A = 46.1)]. The data from this study indicates that a therapeutic regimen of high speed voluntary muscle contractions is effective in decreasing muscle soreness and facilitating return of normal muscular performance. J Orthop Sports Phys Ther 10(12):499-507.     

透明质酸钠治疗膝骨性关节炎的临床效果及分析

目的　观察透明质酸钠 (sodium hyaluronate,SH)关节腔内注射治疗膝骨性关节炎 (osteoarthritis,OA)的临床效果及治疗前后关节液中自由基和炎性介质含量的变化。　方法　 92例 (111膝 ) OA患者 ,其中男 30例 ,女6 2例 ;年龄 2 1～ 71岁 ,平均 4 7.5岁。分轻度组 5 1膝 ,中度组 35膝 ,重度组 2 5膝。关节内每周注射 SH2 0 mg一次 ,共 5次 ,按 L ysholm膝关节功能评分比较治疗前后关节症状和功能的改善情况 ,并测定第 1、2和 5周 SH注射前和注射后 3个月抽取的关节液中一氧化氮 (nitric oxide,NO)、超氧化物歧化酶 (superoxide dismutase,SOD)、丙二醛 (malonicdialodehyde,MDA)和白细胞介素 1β(interlukin1β,IL- 1β)、肿瘤坏死因子 α(tumour necrosis factorα,TNF- α)的含量。　结果　随访 3个月 ,治疗效果优 4 2膝 ,良 38膝 ,可 2 1膝 ,差 10膝 ,优良率 72 .1%。病情越轻 ,治疗见效越早 ,疗效越好。SH治疗后轻、中度组患者关节液中 ,氧自由基含量和 IL- 1β、TNF- α含量明显下降 (P<0 .0 5 ) ,重度组变化不显著 (P>0 .0 5 ) ;SH对 NO含量影响较小 ,只有轻度组治疗后 3个月较治疗前明显减少 (P<0 .0 5 ) ,中、重度组变化不大 (P>0 .0 5 )。　结论　 SH关节腔内注射治疗膝 OA,可缓解临床症状 ,改善     

Quadriceps muscle strength and its relationship to radiographic knee osteoarthritis in Japanese elderly

Background

Knee osteoarthritis (OA) is a multifactorial disease and strongly affected by mechanical factors. The aims of the present study were to assess validity and reliability of a new muscle strength measuring device, the Quadriceps Training Machine (QTM) and evaluate the relationship between quadriceps strength measured by QTM and radiographic knee OA by epidemiological survey.

Methods

The isometric knee extension muscle strength of QTM was compared with BIODEX in 24 healthy adults. Then, the relationship between radiographic knee OA and quadriceps strength using QTM was investigated with 2,032 knees in 1,016 subjects by an epidemiological survey (Matsudai Knee Osteoarthritis Survey).

Results

Significant correlation was observed between QTM and BIODEX (r = 0.69, 0.82). In the Matsudai Knee Osteoarthritis Survey, the prevalence of radiographic OA (grade II or higher upon Kellgren–Lawrence classification) was: 13, 36.9, 67.8, and 86.5 %, regarding women in their fifties, sixties, seventies, and eighties, respectively, and was 1.7, 13.4, 33.5, and 66.2 % regarding men, respectively. Quadriceps muscle strength declined following 50 years of age, and significant decline was observed in the their sixties and seventies. Quadriceps muscle strength of the OA group (grades II, III and IV) was significantly declined compared with that of the Non-OA group (grade-0 and I). Furthermore, the tendency of the muscle strength level to decline with the progression of knee OA grade was particularly observed between grade 0 and grade I in both men and women and between grade I and grade II in men.

Conclusion

The relationship between radiographic knee OA and quadriceps strength was quantitatively evaluated by an epidemiological survey, and we found a correlation between knee OA and the decline in quadriceps strength. Furthermore, it was suggested that the decline in quadriceps muscle strength may be more strongly related to the incidence of knee OA than to its progression.     

Variations in Neuromuscular Activity of Thigh Muscles During Whole-Body Vibration in Consideration of Different Biomechanical Variables

The intention of this study was to systematically analyze the impact of biomechanical variables in terms of different vibration frequencies, amplitudes and knee angles on quadriceps femoris and hamstring activity during exposure to whole-body vibration (WBV). 51 healthy men and women (age 55 ± 8 years) voluntary participated in the study and were randomly allocated to five different vibration-frequency groups. Each subject performed 9 static squat positions (3 amplitudes x 3 knee angles) on a side alternating vibration platform. Surface electromyography (EMG) was used to record the neuromuscular activity of the quadriceps femoris and hamstring muscles. Maximal voluntary contractions (MVCs) were performed prior to the measurements to normalize the EMG signals. A three-way mixed ANOVA was performed to analyze the different effects of the biomechanical variables on muscle activity. Depending on the biomechanical variables, EMG muscle activity ranged between 18.2 and 74.1 % MVC in the quadriceps femoris and between 5.2 and 27. 3 % MVC in the hamstrings during WBV. The highest levels of muscle activation were found at high frequencies and large amplitudes. Especially in the quadriceps femoris muscle, a WBV frequency of 30 Hz led to a significant increase in muscle activity compared to the other tested frequencies. However, it seems that knee angle is only relevant for the quadriceps femoris muscle. The results of this study should give more information for developing individual training protocols for WBV treatment in different practical applications.

Key Points

• WBV leads to a higher muscle activity of the quadriceps femoris than of the hamstrings.
• The maximum levels of muscle activity were significantly reached at high amplitude and high frequency.
• The knee angle only significantly affects the quadriceps femoris.
• Certain combinations of the biomechanical variables have similar effects on the level of muscle activity.

Key words: Vibration training, surface electromyography, muscle strength, muscle tuning     

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.     

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.     

An in vitro study of anterior cruciate ligament strain induced by quadriceps and hamstrings forces

Strain in the anteromedial fibers of the anterior cruciate ligament [ACL(am)] was studied in six cadaver knees. ACL(am) strain was measured in five knees during the application of isometric quadriceps forces alone and simultaneously applied isometric quadriceps and hamstrings forces at 10 degrees increments from 0 degrees to 90 degrees of knee flexion. ACL(am) strain during muscle loading was measured with respect to the ACL(am) strain measured with the knee in its resting position (neutral or near neutral position). A sixth knee was used to investigate the reproducibility of the resting position and quadriceps-induced ACL(am) strains. The strains induced in the ACL(am) by the quadriceps were significantly greater than 0 at knee flexion angles from 0 to 40 degrees and not significantly different from 0 for 50 to 90 degrees. The ACL(am) strains induced by simultaneously applied hamstrings and quadriceps forces were not significantly different from 0 at any of the knee flexion angles tested. Simultaneously applied hamstrings and quadriceps forces significantly reduced ACL(am) strain at 10, 20, and 90 degrees of knee flexion compared to the ACL(am) strain induced by quadriceps forces alone. The hamstrings are potentially capable of both significantly reducing and negating quadriceps-induced ACL(am) strain at 10 and 20 degrees of knee flexion.     

Effect of Longitudinal Versus Transverse Electrode Placement on Torque Production by the Quadriceps Femoris Muscle during Neuromuscular Electrical Stimulation

The purpose of this study was to evaluate the effect of electrode placement in relation to muscle design for producing muscle torque when using neuromuscular electrical stimulation (NMES). Thirty-five healthy subjects (19 men, 16 women) participated in this study on a voluntary basis. All subjects were tested for maximum voluntary isometric contraction (MVC) of their dominant quadriceps femoris muscle while seated on an isokinetic dynamometer. NMES to subject tolerance was used while determining the effect of electrode placement (longitudinal and transverse) on the torque. Findings show that the longitudinal electrode position produces significantly more torque than the transverse position when the knee extensor muscles are electrically stimulated by the same current amplitude. Physical therapists should be aware of this technique when using NMES clinically to produce muscle torque. J Orthop Sports Phys Ther 1990;11(11):530-534.     

Arthroscopic lavage of osteoarthritic knees.

A strong clinical impression exists that joint lavage often provides symptomatic relief for painful osteoarthritis of the knee. A controlled trial was conducted to test this hypothesis. A group of 37 painful osteoarthritic knees were treated by arthroscopic lavage and physiotherapy, and a control group of 24 knees were treated by physiotherapy alone. There was better relief of pain in the lavage group, and the effect was still present at one year. An improvement in the signs of inflammation lasted for about three months. Pain was relieved more effectively in patients with slight radiographic changes than in those with advanced changes. Our results confirm the effectiveness of joint lavage in the management of painful osteoarthritis of the knee.     

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     

Muscle performance about the knee joint in patients who had distal femoral replacement after resection of a bone tumor. An objective study with use of gait analysis

BACKGROUND: The treatment of a malignant bone tumor in the distal aspect of the femur often requires great sacrifice of bone and muscle. The extent of quadriceps removal has been reported to influence the long-term functional efficiency of a patient's gait. The objective of the present study was to determine gait function as it relates to the residual quadriceps strength and to the specific component or components of the quadriceps removed in patients treated with total knee replacement because of a malignant bone tumor in the distal aspect of the femur. METHODS: Sixteen patients were evaluated after implantation of a modular hinged cementless knee prosthesis. The patients were assigned to two groups on the basis of the different components of the quadriceps muscle that were resected. Group 1 consisted of five patients who had removal of the vastus medialis and the vastus intermedius and two who had removal of the vastus medialis only. Group 2 consisted of nine patients who had removal of the vastus lateralis and the vastus intermedius. Residual muscular strength about the treated knee was measured by voluntary maximum contraction isometric testing. Foot-ground reaction forces, kinematic and kinetic findings, and electromyographic activity during free-speed walking were recorded. RESULTS: The kinematic study showed that the patients in Group 1 tended to have a stiff-knee gait during stance, whereas those in Group 2 (in which the vastus medialis was spared) had a more regular flexion-extension knee pattern. Electromyographic findings showed that a higher percentage of patients in Group 1 had reduced or absent rectus femoris activity during the loading response. Compared with the contralateral side, knee-extension strength in the treated limb was decreased in both groups. However, there were no significant differences between the groups with respect to the pattern of strength loss. CONCLUSIONS: Good gait function can be achieved in patients with a distal femoral tumor that is treated with distal femoral resection, partial excision of the quadriceps, and total knee arthroplasty with insertion of a hinged prosthesis. Patients in whom the vastus lateralis and vastus intermedius were removed had better gait performance and a more physiological knee-loading pattern than did patients in whom the vastus medialis was removed.     

Intensive physical therapy after fractures of the femoral shaft

22 patients with fractures of the femoral shaft were divided into 2 groups. One group (12 patients) were given the standard postoperative physiotherapy and the remainder (10 patients) received intensive physiotherapy. Clinical examination of the knee joint was performed 2, 4 and 9 weeks postoperatively. The patients' mean age was 31 years; 15 of them were men. The fractures in 18 patients were treated with intramedullary nailing, 2 with a long-shanked Jewett nail and 2 with AO-nailing. Mobilisation and quadriceps atrophy of the injured limb of the patients given intensive physiotherapy appeared to improve faster than in the patients of the routine physiotherapy group. Nine weeks after the operation the range of knee movement had normalised in the cases given intensive physiotherapy. The flexion strength of the knee in the operated limb was close to the values for the normal limb after nine weeks, but the extension strength was still 40-66% below the values for the healthy limb. The greatest increase in muscle power occurred during the first four postoperative weeks. Intensive physiotherapy seems to hasten the recovery of quadriceps strength of the patients with fractures of the femoral shaft, and to shorten the duration of sick leave of the patients operated on by closed intramedullary nailing.