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.     

Surgical Approaches in Total Knee Arthroplasty: A Meta-Analysis Comparing the Midvastus and Subvastus to the Medial Peripatellar Approach

Subvastus, midvastus and medial parapatellar approaches are the most popular approaches in total knee arthroplasty (TKA). However, the superior approach in TKA still remains controversial. We therefore conducted a meta-analysis to quantitatively compare the midvastus and subvastus approaches to the medial parapatellar approach in TKA. A total of 32 randomized controlled trials (RCTs) with 2451 TKAs in 2129 patients were included in this study. The meta-analysis suggested that, when compared with the medial parapatellar approach, the midvastus approach showed better outcomes in pain and knee range of motion at postoperative 1–2 weeks but also was associated with longer operative time; the subvastus approach showed better outcomes in knee range of motion at postoperative 1 week, straight leg raise and lateral retinacular release.     

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.     

Is Minimally Invasive Surgery in Total Knee Arthroplasty Really Minimally Invasive Surgery?

Minimization of soft-tissue damage is one of the primary purposes behind the application of minimally invasive surgery (MIS) in total knee arthroplasty (TKA). A consecutive series of 147 TKAs were enrolled in the present study, with 96 MIS-TKAs using 11 quadriceps-sparing, 46 subvastus, 32 midvastus, and 7 parapatellar approaches and 51 conventional TKAs using 22 subvastus, 9 midvastus, and 20 parapatellar approaches. Serum levels of creatinine phosphokinase, myoglobin, aldolase, lactate dehydrogenase, glutamic oxaloacetic transaminase, and creatinine were measured on postoperative days 0, 1, 2, 4, 7, and 14. Postoperative rising index (RI) was expressed as a proportion of the preoperative value. When RIs were compared between MIS-TKA and conventional TKA, no significant differences were found for any enzymes. Interestingly, the midvastus approach displayed the highest RIs for creatinine phosphokinase and myoglobin between the 4 vastus-splitting approaches. Consequently, degree of muscle damage was equivalent between MIS-TKA and conventional TKA, whereas types of vastus-splitting approach appeared closely related to muscle damage.     

膝关节骨性关节炎患者股四头肌肌力相关指标变化及其与疼痛程度的关系

目的分析膝关节骨性关节炎（KOA）患者股四头肌肌力相关指标变化情况及其与不同疼痛程度之间的关系,为康复治疗提供临床依据。方法选取2013年6月至2014年6月广州医科大学附属第二医院收治的30例KOA患者作为观察组,将同期体检中心随机选取的30例健康志愿者作为正常对照组。使用电刺激与随意收缩叠加法对研究对象的股四头肌最大随意等长收缩相对肌力（rMVC）、肌肉动员能力（MA）和肌力储备能力（RCMS）进行测量,按照视觉模拟量表（VAS）评分评估KOA患者的疼痛程度,分析不同水平VAS评分股四头肌肌力相关指标的变化。结果观察组患者股四头肌rMVC、MA明显低于对照组,而RCMS明显高于对照组,两组比较,差异均有统计学意义（P〈0.05）。不同水平VAS评分患者股四头肌rMVC、MA及RCMS比较,差异均有统计学意义（P〈0.05）。结论与正常人比较,KOA患者股四头肌肌力降低,肌肉动员能力减弱,但其储备能力有所提高;患者疼痛程度与股四头肌肌力关系密切。提示可通过针对性康复训练提升KOA患者神经-肌肉交联系统的控制能力,增强股四头肌肌力,以实现缓解疼痛、提高关节稳定性、改善临床疗效的目的。     

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.     

Muscle torques in total knee arthroplasty with subvastus and parapatellar approaches

The current study was designed to compare muscle torques when using the subvastus and parapatellar approaches for unilateral total knee arthroplasty. Twelve female patients had unilateral total knee arthroplasty with the subvastus approach from January 1997 to June 1998. The historic control group consisted of 16 female patients who had unilateral total knee arthroplasty with the parapatellar approach from July 1994 to January 1997. Six and 12 months after surgery, a Cybex dynamometer was used to measure isometric and isokinetic muscle strength. Two parameters were used to compare the two approaches, the first parameter was the difference in peak torque between the surgically treated knee and the baseline value for the healthy knee, and the second parameter was the hamstring to quadriceps peak-torque ratio, again using the value for the healthy knee as baseline. The subvastus approach resulted in an initial higher peak torque in the quadriceps 6 months after surgery, but this difference became insignificant 12 months postoperative. Using the subvastus approach, the hamstring to quadriceps peak-torque ratio reached the normal range (0.50-0.80) sooner than was the case using the parapatellar approach. There is a phenomenon of cross adaptation of the untreated knee to the surgically treated knee, and knees operated on by the subvastus approach showed functional recovery at an earlier date than those operated on by the parapatellar approach.     

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.     

Comparative Efficacy of the Different Surgical Approaches in Total Knee Arthroplasty: A Systematic-Review and Network Meta-Analysis

BackgroundSeveral surgical approaches including midvastus, subvastus, mini-parapatellar, quadriceps-sparring (QS) and parapatellar are currently used to perform total knee arthroplasty (TKA). Since none of published study exhibited a simultaneous comparison of all of them, a network meta-analysis has been conducted to compare the most widely used knee surgical approaches regarding the improvement of functional outcomes and the range of motion (ROM).MethodsRandomised controlled trials (RCTs) comparing TKA approaches were searched in electronic databases, major orthopedics journals, and oral communications, ClinicalTrials.gov and WHO International Clinical Trials Registry Platform until May 1st, 2020. Two reviewers independently selected trials and extracted data. The primary outcomes were functional scores at 6 months post-surgeryevaluated by KSS and WOMAC, and the ROM.ResultsSixty RCTs involving 5042 patients with 5107 TKA were included. No significant differences between different approaches were found for the KSS assessment or the WOMAC at 6 months. The mean of ROM at 6 months post-surgery were higher in the subvastus group than in all the others surgical approaches. The difference of ROM with subvastus approach was 7.3° (95% CI ?14.1 to ?0.1) with the midvastus approach, 11.1° (95% CI ?18.7 to ?2.8) with mini-parapatellar, 8.9° (95% CI ?14.2 to ?3.1) with standard parapatellar, and 9.2° (95% CI ?16.1 to ?1.8) with QS.ConclusionNo differences were found in functional outcomes over short or medium terms but subvastus seemed to increase the ROM at 6 months post-surgery. Until or unless future studies can demonstrate a long-term benefit, based on these results all studied surgical approaches to perform a TKA are equal.Level of EvidenceNetwork meta-analysis. Level 1.     

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]     

Electromyographic analysis of a modified maneuver for quadriceps femoris muscle setting with co-contraction of the hamstrings.

A "quadriceps femoris muscle setting" is isometric quadriceps femoris exercise which can be widely used in early knee rehabilitation. However this exercise cannot obtain enough co-contraction of the hamstrings. Isolated quadriceps femoris contraction in knee extension imposes severe strain to anterior cruciate ligament. We succeeded in developing a simple training maneuver that is effective in obtaining co-contraction of the hamstrings--a modified maneuver for the quadriceps femoris muscle setting with the contralateral lower limb raised (MQS). In this study, we analyzed the effect of this maneuver by EMG quantification. Twenty-eight healthy young adult men performed sequential trials consisting of normal quadriceps femoris muscle setting (NQS) and MQS. Electromyographic activity was recorded from surface electrodes on the gluteus maximus, vastus medialis, rectus femoris, vastus lateralis, semitendinosus and biceps femoris (long head), and normalized to values derived from maximal isometric trials. The % maximal voluntary isometric contraction (%MVIC) of the vastus medialis, vastus lateralis and rectus femoris did not vary in the each maneuver. However, the %MVIC of the hamstrings varied significantly in the MQS. This study suggests that effective co-contraction of the hamstrings can be obtained in MQS by adjusting the load to the raised lower limb.     

股内侧肌下方入路并3D打印导板辅助全膝关节置换术的临床应用

目的评估股内侧肌下方入路并3D打印导板辅助全膝关节置换术的治疗效果。 方法回顾分析2015年3月至2016年3月沈阳市骨科医院关节外科应用股内侧肌下方入路并3D导板辅助全膝关节置换术治疗的骨关节炎患者63例,分别于术前、术后3个月进行视觉模拟评分（VAS评分）、膝关节功能评分（HSS评分）及髌骨Feller评分的评估。并于术前、术后3个月及6个月对患者股四头肌肌力及膝关节活动度进行评定。于术前、术后1个月进行伸直位Q角及其髌骨外推Q角,屈曲30°位Q角及其髌骨外推Q角的测量。 结果所有手术均顺利完成,63例患者均获完整随访,随访时间12~18个月,平均随访（14.5±2.7）个月。患者术后VAS评分[（1.8±0.4）分]、HSS评分[（93±6）分]和髌骨Feller评分[（26±4）分]较术前[（6.8±2.2、37±6、16±6）分]有明显改善（t=18.223,t=-51.741,t=-11.485,P<0.05）;术后6个月患者股四头肌肌力[（80±8）分]较术前[（74±8）分]有改善,差异有统计学意义（F=20.771,P<0.05）。患者术后3个月膝关节屈伸活动范围[屈：（118±5）°,伸：（1.0±0.9）°]较术前[屈：（80±14）°,伸：（3.8±1.8）°]有改善,差异具有统计学意义（F=306.062,F=105.050,P<0.05）。伸直位和屈曲30°位Q角及其髌骨外推Q角,以及两种状态下Q角差值,术后较术前均有明显改善,差异均有统计学意义（伸直位：t=20.489,t=6.753,t=4.891,屈曲位：t=21.497,t=2.853,t=5.698,P<0.05）。 结论应用股内侧肌下方入路并3D打印导板辅助下完成人工全膝关节置换术,创伤小、效果好、并发症少。     

Patellar Eversion Does Not Adversely Affect Quadriceps Recovery Following Total Knee Arthroplasty

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

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.     

连续收肌管阻滞和连续股神经阻滞对膝关节置换术患者术后镇痛和早期功能康复的影响

目的 比较连续收肌管阻滞(adductor canal block,ACB)和连续股神经阻滞(femoral nerve block,FNB)在膝关节置换术(total knee arthroplasty,TKA)患者术后镇痛的效果和对早期功能康复的影响.方法 择期拟行单侧TKA患者60例,采用随机数字表法分为两组(每组30例):连续ACB组(A组)和连续FNB组(F组).术中采用全凭静脉麻醉.两组在麻醉诱导前分别行超声引导下ACB和FNB,并放置神经周围导管.术毕经神经周围导管予0.2％罗哌卡因实施患者自控周围神经阻滞镇痛.记录术后4、8、12、24、48 h静息和运动(膝关节被动屈曲45°)疼痛数字评分(numeric rating scale,NRS)、患肢股四头肌肌力Lovett评分和患肢运动阻滞改良Bromage评分.记录:术后1、2、3、14 d膝关节最大主动/被动活动度,术后14 d美国纽约特种外科医院(hospital for special surgery,HSS)膝关节功能评分,术后第1次下床活动时间和术后膝关节主动屈膝90°时间.记录术后48 h内镇痛泵有效按压次数和补救镇痛率.结果 两组术后静息和运动NRS评分、镇痛泵有效按压次数和补救镇痛率等比较,差异均无统计学意义(P＞0.05).A组术后12 h内患肢股四头肌肌力Lovett评分明显高于F组(P＜0.05)、息肢运动阻滞改良Bromage评分明显低于F组(P＜0.05).A组术后1、2、3d膝关节最大主动活动度明显大于F组(P＜0.05),但膝关节最大被动活动度、术后14 d膝关节最大主动活动度、术后14 d膝关节HSS评分以及术后第1次下床活动时间和术后膝关节主动屈曲90°时间两组间比较差异均无统计学意义(P＞0.05).结论 连续ACB和连续FNB可为TKA患者提供等同的术后镇痛效果,而且对早期功能康复具有相似的效果.     

Comparison of early postoperative rehabilitation outcome following total knee arthroplasty using different surgical approaches and instrumentation

PURPOSE: To assess early postoperative rehabilitation outcome following computer-assisted total knee arthroplasty (TKA) or standard instrumentation TKA using a medial parapatellar or subvastus approach. METHODS: A prospective controlled trial of 70 consecutive patients undergoing TKA with a low contact stress rotating platform prosthesis was conducted. Patients were randomised to receive surgery with either computer navigation or standard instrumentation. A medial parapatellar or subvastus approach was used according to the surgeons' preference. Outcome measures included preoperative knee function, intra-operative factors, and postoperative rehabilitation. RESULTS: Duration of surgery was significantly longer when using computer navigation; however, operating time decreased with greater experience. A higher incidence and duration of early postoperative quadriceps dysfunction was associated with computer-assisted TKA through the medial parapatellar approach than through the subvastus approach or TKA performed with standard instrumentation. No patient who received surgery through the subvastus approach had a lag of more than 20 degrees, at 48 hours postoperatively, regardless of the instrumentation used. CONCLUSION: Computer-assisted TKA through a medial parapatellar approach was associated with delayed recovery of the quadriceps during early postoperative rehabilitation. This was due to the additional quadriceps dissection required to place the femoral tracking array. The subvastus approach is therefore recommended for computer-assisted TKA.     

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.     

Clinical comparison of the midvastus and medial parapatellar surgical approaches.

The medial parapatellar approach and the midvastus approach are the two most commonly used surgical approaches in total knee replacement. This study compared surgical and clinical parameters associated with both surgical approaches in primary total knee replacement. One hundred nine patients who underwent bilateral primary total knee replacements had a medial parapatellar approach to one knee and a midvastus approach to the opposite knee. The prosthetic design and physical therapy were identical in all 109 patients. The patients and physical therapists were blinded to the type of approach used on each knee. The comparison included the surgical parameters of difficulty of exposure, surgical time, incidence of lateral retinacular release, and total blood loss. The clinical parameters of pain, range of motion, ability to perform a straight leg raise, and complications were compared at 8 days, 6 weeks and 6 months. The comparison between the two surgical approaches showed a statistically significant difference in four parameters, all of which favored the midvastus approach. The patients who had the midvastus approach required fewer lateral retinacular releases, had less pain at 8 days, had less pain at 6 weeks, and had a higher incidence of ability to straight leg raise at 8 days. There was no statistical difference between the two surgical approaches in all other surgical and clinical parameters. There was no increased difficulty of exposure using the midvastus approach when compared with the medial parapatellar approach even in patients with severe varus or valgus deformities. Notably, all clinical parameters were equal at 6 months. From a clinical standpoint, the midvastus approach had an advantage over the medial parapatellar approach because the patients had significantly less pain and had the ability to straight leg raise at 8 days. Because the managed care environment dictates a shorter hospital stay, patients who have the midvastus surgical approach have less pain and earlier control of the operative leg, and may be discharged from the hospital earlier. However, the clinical results at 6 months based on the patient's pain relief, range of motion, and ability to straight legraise were identical between the two surgical approaches.     

Electromyographic evaluation of the midvastus approach

Compared with the standard median parapatellar approach, the muscle-splitting midvastus approach to the knee has led to claims of an easier and earlier recovery after total knee arthroplasty, but some investigators have questioned whether the midvastus approach damages the vastus medialis obliquus. We used electromyographic and nerve conduction studies to evaluate whether we could document any such damage. Twenty patients undergoing bilateral total knee arthroplasty were randomized prospectively for the treatment of 1 knee with each of the 2 approaches. Radiographs, electromyographies, nerve conduction studies, range-of-motion tests, and Knee Society function and pain tests were conducted preoperatively and at 6 weeks postoperatively. If the electromyography or nerve conduction tests were abnormal at 6 weeks, the tests were repeated at 12 weeks. At the final follow-up, these studies showed no evidence of muscle denervation. The midvastus approach appears to be a safe alternative for knee arthrotomy for total knee arthroplasty without concerns for damage to the vastus medialis obliquus.     

Comparing outcomes of medial parapatellar and subvastus approaches in total knee arthroplasty: a randomized controlled trial

The medial parapatellar (MP) approach in total knee arthroplasty is more common, but the subvastus (SV) approach is less insulting to the quadriceps. Whether the SV approach affords better outcomes was investigated using 90 participants with knee osteoarthritis, randomized to receive either SV or MP approaches and followed for 18 months. The primary outcome was the American Knee Society Score (AKSS); secondary outcomes included pain, knee range, quadriceps lag, Oxford Knee Score, 3-m timed "Up and Go" test, days to straight leg raise, surgeon perceived difficulty, operation duration, and length of stay. Analysis (n = 76) revealed no significant difference in AKSS (P = .076) or other outcomes, except the following: AKSS Functional scores at 12 and 18 months, favoring the MP (P = .032 and P = .028 respectively); surgeon's perceived difficulty, favoring the MP (P = .001); and days to straight leg raise, favoring the SV (P = .044). This study found that the SV approach offers no clinical benefit over the MP approach.