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.     

运动想象训练对全膝关节置换术患者干预效果的分析

目的系统评价运动想象训练(MIT)对全膝关节置换手术(TKA)患者的干预效果。 方法检索荷兰医学文摘数据库(EMBASE)、PubMed、Web of Science、Cochrane Library、卫生保健及护理学数据库(CINAHL)、中国生物医学文献数据库(CBM)、中国知网、万方、维普数据库,收集关于MIT对TKA患者干预效果的随机对照试验。筛选研究对象为采用MIT联合常规物理康复或只进行常规物理康复的TKA术后患者,结局指标涉及股四头肌肌力、膝关节活动范围(ROM)、疼痛视觉模拟评分(VAS)、计时起立－行走测试(TUG)。运用Cochrane协作工具对纳入研究的质量进行评估,采用Stata 16.0软件进行Meta分析。 结果共纳入8篇文献,264例患者。Meta分析结果显示：MIT组与对照组相比,能显著提升TKA患者股四头肌肌力[标准化均数差(SMD)＝0.67,95%置信区间(CI)(0.37,0.96),P<0.001]、膝关节ROM [SMD＝0.60,95%CI(0.06,1.15),P＝0.032],降低VAS评分[SMD＝－0.64,95%CI(－1.00,－0.28),P＝0.001],但对TUG的影响无统计学意义[SMD＝－0.59,95%CI(－1.21,0.03),P＝0.063]。亚组分析显示,在慢性康复期(术后≥2周),MIT能显著提升膝关节ROM[SMD＝1.65,95%CI(0.84,2.45),P<0.001],降低VAS评分[SMD＝－0.63,95%CI(－1.10,－0.16),P＝0.008],而在急性康复期(术后24 h)MIT对膝关节ROM与VAS的影响无统计学意义(P>0.05)。 结论当前证据表明,MIT联合常规物理康复能够显著提升TKA术后患者股四头肌力量、膝关节ROM,缓解疼痛。但MIT对膝关节ROM与疼痛的干预效果受康复阶段的影响。     

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

SYNOPSIS: 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.     

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.     

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.     

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.     

Quadriceps weakness preferentially predicts detrimental gait compensations among common impairments after total knee arthroplasty

Patients with total knee arthroplasty (TKA) have large deficits in physical performance in comparison to their healthy age‐matched peers. Limb asymmetry stemming from less relative load borne by the surgical limb during daily mobility is associated with diminished performance and worsens with greater mobility demands. How common targets of postoperative care, such as muscle weakness, lower limb extension power, residual knee pain, and poor balance confidence can influence asymmetrical limb loading remains unclear. Forty‐six patients with unilateral TKA underwent testing of impairments and motion analysis during 10° decline walking at 3 and 6 months postoperatively. At 3 months, only quadriceps femoris strength asymmetry was found to be significantly related to both total support moment (M_T) (β = 0.431; p < 0.001) and knee extensor moment (M_K) (β = 0.493; p < 0.001) asymmetry. Again at 6 months, only quadriceps strength asymmetry was related to M_T (β = 0.432; p < 0.001) and M_K (β = 0.534; p < 0.001) asymmetry. Quadriceps strength significantly improved over time in both limbs, however, deficits between limbs remained. Persistent quadriceps weakness is a key factor associated with walking compensation patterns that are limiting the capacity for greater physical performance of patients with TKA. The pronounced asymmetry in limb and knee loading at 3 months remains unchanged until at least 6 months after surgery, and its association with quadriceps strength asymmetry does not substantially change over time. While other factors may also prompt gait compensations, emphasis on improved quadriceps strength should be a focus of efforts to resolve gait compensations and enhance physical performance outcomes. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2355–2363, 2018.

     

Minimally Invasive Total Knee Arthroplasty Improves Early Knee Strength But Not Functional Performance : A Randomized Controlled Trial

A prospective, randomized investigation compared early clinical outcomes of total knee arthroplasty (TKA) using conventional or minimally invasive surgical (MIS) approaches (n = 44). Outcome measures included isometric quadriceps and hamstrings strength, quadriceps activation, functional performance, knee pain, active knee range of motion, muscle mass, the Short Form-36, and Western Ontario and McMaster University Osteoarthritis Index, assessed preoperatively and 4 and 12 weeks after TKA. Four weeks after TKA, the MIS group had greater hamstring strength (P = .02) and quadriceps strength (P = .07), which did not translate to differences in other outcomes. At 12 weeks, there were no clinically meaningful differences between groups on any measure. Although MIS may lead to faster recovery of strength in patients undergoing TKA, there was no benefit on longer-term recovery of strength or functional performance.     

Safety, feasibility, and efficacy of negative work exercise via eccentric muscle activity following anterior cruciate ligament reconstruction

STUDY DESIGN: Randomized, matched design. BACKGROUND: Optimal rehabilitation following anterior cruciate ligament reconstruction (ACL-R) requires safe and effective interventions. Negative work exercise (via eccentric muscle activity) has the potential to be highly effective at producing large quadriceps size and strength gains early after ACL-R. The purpose of this investigation was to evaluate the short-term safety and efficacy of adding a progressive negative work exercise program via eccentric (ECC) ergometry early after ACL-R. METHODS AND MEASURES: Beginning 3 weeks after ACL-R, 32 participants were randomly assigned into either a 12-week traditional (TRAD) or ECC exercise program. Safety was assessed by measuring knee pain, thigh pain, knee effusion, and knee stability prior to surgery and at 3,15, and 26 weeks after surgery. Efficacy was assessed by measuring negative work output during the 12-week training program and by measuring functional ability (ie, quadriceps peak torque, hopping distance, self-reported functional ability and activity level scales) prior to surgery and 26 weeks after ACL-R. RESULTS: There were no significant differences between groups in measures of knee and thigh pain, effusion, or stability at any period after surgery. Negative work output increased systematically throughout training, while knee and thigh pain remained at relatively low levels. A significant group-by-time interaction was observed for quadriceps peak torque, hopping distance, and activity level (P< or =.02). Quadriceps strength and hopping distance of the involved limb improved by a significantly greater amount in the ECC group compared to the TRAD group (P<.01). Activity level decreased to a lesser extent in the ECC group compared to the TRAD group (P =.02). CONCLUSIONS: Negative work via an ECC intervention was implemented safely after ACL-R. The addition of negative work exercise also induced superior short-term results in strength, performance, and activity level after surgery.     

Prospective study of changes in impairments and disabilities after anterior cruciate ligament reconstruction.

STUDY DESIGN: Single-group, repeated-measures prospective study. OBJECTIVES: To analyze changes in impairments and disabilities among patients with anterior cruciate ligament (ACL) reconstruction and to assess the relationships between the impairment and disability outcome measures from 3 months to 2 years following ACL reconstruction. BACKGROUND: Outcomes after ACL reconstruction can be categorized as impairments or disabilities. The relationship between impairments and disabilities may be crucial to understanding physical therapy interventions and predicting long-term outcome. METHODS AND MEASURES: Sixty patients who had undergone ACL reconstruction participated in the study. Impairment measures were range of motion, pain, knee-joint laxity, and muscle performance using isokinetic muscle tests. Disability measures were the Cincinnati knee score and lower limb performance using the triple-jump and stair-hop tests. Follow-up times were 3 and 6 months and 1 and 2 years after surgery. RESULTS: The Cincinnati knee score results show significant improvement 1 year after surgery (84.2 +/- 13.6) compared with 6 months (76.8 +/- 13.7) and 3 months (67.4 +/- 16.3) after surgery. Quadriceps total work (percentage of normal leg) significantly improved 2 years after surgery (92.6 +/- 14.1%) compared with 1 year after surgery (81.6 +/- 16.8%). Between 37 and 75% of the variability in the Cincinnati knee score could be explained by variation in the impairment variables, and quadriceps muscle performance and pain were the most significant predictors of disability. Extension deficit and pain at 3 months were significantly related to the Cincinnati knee score at the 2-year follow-up. CONCLUSIONS: Up to 2 years may be needed to regain normal quadriceps muscle performance following ACL reconstruction. Pain and quadriceps muscle performance explained most of the variability in the Cincinnati knee score.     

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.     

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.     

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.     

不同股神经阻滞对全膝关节置换术后疼痛和肌力的影响

目的比较连续股神经阻滞(CFNB)与单次股神经阻滞(SFNB)联合关节腔周围注射(PAI)对全膝关节置换术(TKA)术后早期疼痛和肌力的影响。 方法回顾性分析2020年1月至2020年12月期间于北京大学第三医院骨科行TKA的患者资料。纳入由同一工作组完成手术及围术期管理且麻醉方式为椎管内麻醉的单侧初次TKA的患者,并排除同侧膝关节有既往手术史、膝关节严重内外翻畸形或严重关节外畸形、术前肌力和肌张力异常患者。患者按镇痛方案分为CFNB组和联合组;比较患者一般信息、手术时间、额外镇痛药物比例及下肢深静脉血栓(DVT)、留置管脱落、阻滞区域感染等并发症差异。分析术后12、24、48、72 h疼痛程度及股四头肌肌力差异。所得数据使用独立样本t检验、卡方检验、Kruskal-Wallis检验、Wilcoxon符号秩检验或方差分析进行统计学分析。 结果共纳入患者144例(CFNB组65例,联合组79例)。两组患者的一般信息、手术时间、额外镇痛药物比例和DVT发生率差异无统计学意义(均为P>0.05);所有患者均未出现留置管脱落、阻滞区域感染等并发症。两组患者12 h和72 h自评视觉模拟评分(VAS)差异无统计学意义(P>0.05)。术后24 h和48 h,CFNB组VAS评分[(1.8±1.3)、(2.6±0.8)]低于联合组[(3.2±0.7)、(4.0±0.8)](t ＝－7.670、10.250,均为P<0.001)。两组患者术后12 h时的肌力差异无统计学意义(P>0.05),CFNB组24、48、72 h的肌力低于联合组(H＝62.944、88.486、120.694,均为P<0.01)。 结论在TKA术后早期,SFNB联合PAI可以达到与CFNB相同的临床镇痛效果,但联合组患者股四头肌肌力恢复更快,且DVT发生风险更小,是TKA术后可取的镇痛方式之一。     

Total knee arthroplasty following patellectomy

Eleven patients with a previous patellectomy and primary total knee arthroplasty (TKA) had chart reviews, recent clinical examinations, evaluation of roentgenograms, rating of knee arthroplasty on a standard scale, and quantitation of quadriceps and hamstring torque using an isokinetic dynamometer. Good to excellent results were present in only five of the 11 knees studied, compared with 11 of 11 patients in a control group with intact patellae. Quadriceps and hamstring torque and strength were diminished relative to the control groups. Factors that correlated with a success or failure of TKA in patients with previous patellectomy included: number of previous knee operations, three or less; presence of severe arthritic changes roentgenographically; and quadriceps performance of greater than 40 ft-lb at 30 degrees/second testing speed. Patients without patellae who lack these favorable prognostic factors for a successful TKA should be strongly considered for bracing or primary arthrodesis, rather than knee arthroplasty.     

Influence of bilateral sequential total knee arthroplasty on functional recovery

Background:

Main concerns of patients undergoing bilateral surgery is the quantum of pain and the progress of functional recovery. We studied functional recovery in terms of pain, range of motion (ROM), SF12, WOMAC scores and a unique TUG (timed up and go) test for patients undergoing unilateral total knee arthroplasty (U/L-TKA) and sequential bilateral total knee arthroplasty (B/L-TKA).

Materials and Methods:

Three groups of 77 consecutive patients (91 knees) were retrospectively compared. They were B/L TKA group (28 knees: 14 patients), Unilateral TKA group with contralateral knee nonoperated i.e., U/L-TKA group (42 knees) and Unilateral TKA with contralateral TKA already done i.e., U/L + C/L TKA group (21 knees). Patients were assessed preoperatively and on postoperative days 3, 5, 14, 42, 90 and 1 year.

Results:

The WOMAC score was statistically better preoperatively in the U/L + C/L TKA group, and SF12 MCS score was statistically better preoperatively in the B/L-TKA group. The TUG test time in the B/L-TKA group was statistically longer on days 3 and 5 as compared to other groups and became comparable by day 14. The TUG score became better than the preoperative value by day 42 in the B/L-TKA group, which took 90 days in other groups.

Conclusion:

The early functional recovery of bilateral TKA patient lags behind that of unilateral TKA patient for the first 5 days, becomes equal by the 14^th day and remains equal till 1 year after surgery. Bilateral TKA patients regain their preoperative functional status by 6 weeks against 3 months for unilateral TKA. The operative status of the contralateral knee makes no difference to early functional recovery after unilateral TKA. With bilateral TKA, there is no difference in pain and ROM parameters.     

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.     

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.     

肥胖患者膝关节表面置换术后的早期康复

目的探讨肥胖患者初次膝关节置换术后早期康复的方法。方法自2009年1月至2012年6月共完成肥胖患者初次膝关节置换42例42膝,男8例,女34例;年龄60～78岁,平均65岁,身体质量指数（BMI）33—52,平均46。术后早期进行持续被动关节运动增加关节活动度（ROM）和进行股四头肌及胭绳肌肌力的强化训练,延长住院时间至术后14d。分别以术前2d、术后2d、1、2、4、8、12、24周作为观察点,使用VAS疼痛评分、WOMAC评分和ROM对膝关节功能及疼痛程度进行评价。结果术后VAS疼痛评分、WOMAC评分低于术前,术后ROM高于术前,差异均有统计学意义。所有指标在术后4周以后均有逐步改善,但差异没有统计学意义。结论肥胖患者膝关节置换术后早期行功能锻炼及适当延长住院时间可以提高膝关节功能。