Quadriceps strength and weight acceptance strategies continue to improve two years after anterior cruciate ligament reconstruction

The anterior cruciate ligament (ACL) is the most commonly-injured knee ligament during sporting activities. After injury, most individuals experience episodes of the knee giving way during daily activities (non-copers). Non-copers demonstrate asymmetrical quadriceps strength and movement patterns, which could have long-term deleterious effects on the integrity of the knee joint. The purpose of this study was to determine if non-copers resolve their strength and movement asymmetries within two years after surgery. 26 Non-copers were recruited to undergo pre-operative quadriceps strength testing and 3-dimensional gait analysis. Subjects underwent surgery to reconstruct the ligament followed by physical therapy focused on restoring normal range of motion, quadriceps strength, and function. Subjects returned for quadriceps strength testing and gait analysis six months and two years after surgery. Acutely after injury, quadriceps strength was asymmetric between limbs, but resolved six months after surgery. Asymmetric knee angles, knee moments, and knee and hip power profiles were also observed acutely after injury and persisted six months after surgery despite subjects achieving symmetrical quadriceps strength. Two years after surgery, quadriceps strength in the involved limb continued to improve and most kinematic and kinetic asymmetries resolved. These findings suggest that adequate quadriceps strength does not immediately resolve gait asymmetries in non-copers. They also suggest that non-copers have the capacity to improve their quadriceps strength and gait symmetry long after ACL reconstruction.     

Analysis of Interlimb Asymmetry in Patients Undergoing Simultaneous Bilateral Total Knee Arthroplasty

Simultaneous bilateral TKA (SBTKA) has been a favored surgical solution due to reduced costs and patient suffering. The purpose of the present study was to investigate the risk factors of asymmetric recovery in patients who underwent SBTKA and whether that affected quality of life. A total of 187 patients undergoing SBTKA were included. During this study, patients underwent physical examination (knee swelling, active range of motion (ROM) of knee and quadriceps strength) and completed three surveys (VAS pain rating, Short Form-36 and requisite information lists in this study). Our results reveal interlimb asymmetries existed at least two years postoperatively. Between-limb differences in active ROM, quadriceps strength, and VAS pain scores were significantly detected in our study. Risk factors included being female, being older, and having high BMI and high levels of anxiety and depression; different diagnosis and different component size could be risk factors. Finally, interlimb differences in VAS pain scores and active ROM were negatively associated with SF-36 scores. However, interlimb differences in swelling and quadriceps strength were unrelated to SF-36 scores. Risk factors of asymmetric recovery should be evaluated and appreciated due to their significant impact on patients’ quality of life. Before performing SBTKA, clinicians should consider possible risk factors and inform patients of asymmetric recovery between limbs, which could help decrease the unnecessary consultations and postoperative patient dissatisfaction.     

Stance and swing phase knee flexion recover at different rates following total knee arthroplasty: An inertial measurement unit study

Total knee arthroplasty (TKA) is the most common joint replacement in the United States. Range of motion (ROM) monitoring includes idealized clinic measures (e.g. goniometry during passive ROM) that may not accurately represent knee function. Accordingly, a novel, portable, inertial measurement unit (IMU) based ROM measurement method was developed, validated, and implemented. Knee flexion was computed via relative motion between two IMUs and validated via optical motion capture (p > 0.05). Prospective analyses of 10 healthy individuals (5M, 50 ± 19 years) and 20 patients undergoing TKA (3 lost to follow up, 10M, 65 ± 6 years) were completed. Controls wore IMUs for 1-week. Patients wore IMUs for 1-week pre-TKA, 6-weeks immediately post-TKA, and 1-week at 1-year post-TKA. Flexion was computed continuously each day (8–12 h). Metrics included daily maximum flexion and flexion during stance/swing phases of gait. Maximum flexion was equal between cohorts at all time points. Contrastingly, patient stance and swing flexion were reduced pre-TKA, yet improved post-TKA. Specifically, patient stance and swing flexion were reduced below control/pre-TKA values during post-TKA week 1. Stance flexion exceeded pre-TKA and equaled control levels after week 2. However, swing flexion only exceeded pre-TKA and equaled control levels at 1-year post-TKA. This novel method improves upon the accuracy/portability of current methods (e.g. goniometry). Interestingly, surgery did not impact maximum ROM, yet improved the ability to flex during gait allowing more efficient and safe ambulation. This is the first study continuously monitoring long-term flexion before/after TKA. The results offer richer information than clinical measures about expected TKA rehabilitation.     

全膝关节置换术对膝关节骨关节炎患者关节功能的影响

目的:探讨全膝关节置换术(TKA)对膝关节骨关节炎患者术后关节功能的影响。方法:回顾性分析2013年8月-2015年8月我院收治的76例膝关节骨关节炎患者的临床资料,所有患者均采用全膝关节置换术治疗。观察并比较患者手术前后膝关节HSS评分、膝关节疼痛目测类比评分(VAS)、膝关节屈曲活动度(ROM)的变化情况。结果:患者术后膝关节HSS评分、膝关节疼痛评分VAS及ROM均明显高于术前,差异具有统计学意义(P0.05);术前HSS评分、膝关节疼痛VAS评分、膝关节ROM、胫骨平台后倾角(PSA)以及股骨前髁偏距(ACO)与术后膝关节HSS评分呈正相关关系,而内翻畸形角度与术后膝关节HSS评分呈负相关关系,差异具有统计学意义(P0.05)。结论:全髋关节置换术能够改善骨关节炎患者的膝关节功能,并且术前膝关节HSS评分、膝关节疼痛VAS评分及PSA与术后患者髋关节功能恢复程度有关。     

Validity and reliability of isometric,isokinetic and isoinertial modalities for the assessment of quadriceps muscle strength in patients with total knee arthroplasty

Reliability of isometric, isokinetic and isoinertial modalities for quadriceps strength evaluation, and the relation between quadriceps strength and physical function was investigated in 29 total knee arthroplasty (TKA) patients, with an average age of 63 years. Isometric maximal voluntary contraction torque, isokinetic peak torque, and isoinertial one-repetition maximum load of the involved and uninvolved quadriceps were evaluated as well as objective (walking parameters) and subjective physical function (WOMAC). Reliability was good and comparable for the isometric, isokinetic, and isoinertial strength outcomes on both sides (intraclass correlation coefficient range: 0.947–0.966; standard error of measurement range: 5.1–9.3%). Involved quadriceps strength was significantly correlated to walking speed (r range: 0.641–0.710), step length (r range: 0.685–0.820) and WOMAC function (r range: 0.575–0.663), independent from the modality (P < 0.05). Uninvolved quadriceps strength was also significantly correlated to walking speed (r range: 0.413–0.539), step length (r range: 0.514–0.608) and WOMAC function (r range: 0.374–0.554) (P < 0.05), except for WOMAC function/isokinetic peak torque (P > 0.05). In conclusion, isometric, isokinetic, and isoinertial modalities ensure valid and reliable assessment of quadriceps muscle strength in TKA patients.     

Effects of walking speed, strength and range of motion on gait stability in healthy older adults

Falls pose a tremendous risk to those over 65 and most falls occur during locomotion. Older adults commonly walk slower, which many believe helps improve walking stability. While increased gait variability predicts future fall risk, increased variability is also caused by walking slower. Thus, we need to better understand how differences in age and walking speed independently affect dynamic stability during walking. We investigated if older adults improved their dynamic stability by walking slower, and how leg strength and flexibility (passive range of motion (ROM)) affected this relationship. Eighteen active healthy older and 17 healthy younger adults walked on a treadmill for 5min each at each of 5 speeds (80-120% of preferred). Local divergence exponents and maximum Floquet multipliers (FM) were calculated to quantify each subject's inherent local dynamic stability. The older subjects walked with the same preferred walking speeds as the younger subjects (p=0.860). However, these older adults still exhibited greater local divergence exponents (p<0.0001) and higher maximum FM (p<0.007) than the younger adults at all walking speeds. These older adults remained more locally unstable (p<0.04) even after adjusting for declines in both strength and ROM. In both age groups, local divergence exponents decreased at slower speeds and increased at faster speeds (p<0.0001). Maximum FM showed similar changes with speed (p<0.02). Both younger and older adults exhibited decreased instability by walking slower, in spite of increased variability. These increases in dynamic instability might be more sensitive indicators of future fall risk than changes in gait variability.     

Neuromuscular activation of quadriceps bellies during tasks performed in the same biomechanical condition in patients undergoing total knee arthroplasty

ObjectiveTo investigate neuromuscular activation of quadriceps bellies during different tasks in patients before and after total knee arthroplasty (TKA).MethodsTwenty-six patients scheduled for TKA and 16 control subjects performed three isometric tasks: knee extension (KE), hip flexion (HF), hip flexion with contralateral hip extension (HFE). Surface electromyography signals of rectus femoris, vastus medialis and vastus lateralis were collected the day before (T0), at one (T1) and three (T2) days after surgery, whereas control subjects underwent a single evaluation. The Root Mean Square peak normalized for its highest value during the three tasks (nRMS-peak) was used as index of maximum neuromuscular activation for each belly. Sixteen patients performed the postoperative assessment, due to the placement of an elastomeric pump aimed at reducing pain in 10 patients.ResultsPatients showed lower rectus femoris nRMS-peak during KE compared to HF and HFE before and after surgery (p < 0.001), as occurred in control subjects. Differently from control subjects, patients showed higher vastus medialis and vastus lateralis nRMS-peak during HF compared to KE at T1 (p = 0.008) and T2 (p = 0.039).ConclusionTKA modified quadriceps neuromuscular activation during different tasks performed the same biomechanical condition. These findings may be considered in planning physiotherapy interventions after TKA.     

Serial Changes of Quadriceps and Hamstring Muscle Strength Following Total Knee Arthroplasty: A Meta-Analysis

This meta-analysis was performed to analyze serial changes in thigh muscles, including quadriceps and hamstring muscles, from before to one year after total knee arthroplasty (TKA). All studies sequentially comparing isokinetic quadriceps and hamstring muscle strengths between the TKA side and the contralateral uninjured limb were included in this meta-analysis. Five studies with 7 cohorts were included in this meta-analysis. The mean differences in the strengths of quadriceps and hamstring muscles between the TKA and uninjured sides were greatest three months after surgery (26.8 N∙m, 12.8 N∙m, P<0.001), but were similar to preoperative level at six months (18.4 N∙m, 7.4 N∙m P<0.001) and were maintained for up to one year (15.9 N∙m, 4.1 N∙m P<0.001). The pooled mean differences in changes in quadriceps and hamstring strengths relative to preoperative levels were 9.2 N∙m and 4.9 N∙m, respectively, three months postoperatively (P = 0.041), but were no longer significant after six months and one year. During the year after TKA, quadriceps and hamstring muscle strengths were lowest after 3 months, recovering to preoperative level after six months, but not reaching the muscle strength on the contralateral side. Relative to preoperative levels, the difference in muscle strength between the TKA and contralateral knees was only significant at three months. Because decrease of strength of the quadriceps was significantly greater than decrease in hamstring muscle strength at postoperative three months, early rehabilitation after TKA should focus on recovery of quadriceps muscle strength.     

Effects of Quadriceps Muscle Fatigue on Stiff-Knee Gait in Patients with Hemiparesis

The relationship between neuromuscular fatigue and locomotion has never been investigated in hemiparetic patients despite the fact that, in the clinical context, patients report to be more spastic or stiffer after walking a long distance or after a rehabilitation session. The aim of this study was to evaluate the effects of quadriceps muscle fatigue on the biomechanical gait parameters of patients with a stiff-knee gait (SKG). Thirteen patients and eleven healthy controls performed one gait analysis before a protocol of isokinetic quadriceps fatigue and two after (immediately after and after 10 minutes of rest). Spatiotemporal parameters, sagittal knee and hip kinematics, rectus femoris (RF) and vastus lateralis (VL) kinematics and electromyographic (EMG) activity were analyzed. The results showed that quadriceps muscle weakness, produced by repetitive concentric contractions of the knee extensors, induced an improvement of spatiotemporal parameters for patients and healthy subjects. For the patient group, the increase in gait velocity and step length was associated with i) an increase of sagittal hip and knee flexion during the swing phase, ii) an increase of the maximal normalized length of the RF and VL and of the maximal VL lengthening velocity during the pre-swing and swing phases, and iii) a decrease in EMG activity of the RF muscle during the initial pre-swing phase and during the latter 2/3 of the initial swing phase. These results suggest that quadriceps fatigue did not alter the gait of patients with hemiparesis walking with a SKG and that neuromuscular fatigue may play the same functional role as an anti-spastic treatment such as botulinum toxin-A injection. Strength training of knee extensors, although commonly performed in rehabilitation, does not seem to be a priority to improve gait of these patients.     

经股内侧肌入路降低全膝关节置换术术后不良反应及促进膝关节功能康复

为评估髌骨旁内侧入路和经股内侧肌入路两种手术技术在全膝关节置换术(total knee arthroplasty,TKA)中的早期功能结果,本研究选取50例2013年3月至2017年3月期间在我院行全膝关节置换数的患者作为研究对象,随机分为两组。一组患者通过髌骨旁内侧入路进行TKA手术,另外一组患者通过经股内侧肌入路方法进行TKA手术。所有患者均只进行一次手术,两组均使用相同类型的植入物。使用视觉模拟评分法(visual analogue scale, VAS)记录疼痛评分,并在术后3周和6周时获得随访数据,包括股四头肌强度和本体感受。结果表明,TKA术后,经股内侧肌入路组患者在休息和运动时表现出明显较低的疼痛(VAS:平均2.13±1.87与2.84±1.76)和(VAS:平均3.11±2.16与3.21±2.02)。此外,经股内侧肌入路组患者在3周((41.2±17.8) Nm vs (27.3±14.1) Nm)和6周((47.4±19.5) Nm vs (35.6±16.2) Nm)显示出优异的等长股四头肌强度。另外,经股内侧肌入路组患者术后本体感觉良好,而两组患者的运动范围相似。研究初步表明,在早期康复期间,经股内侧肌入路方法比髌骨旁内侧入路更有优势。没有观察到与此方法相关的不良影响。因此,经股内侧肌入路应被认为是TKA中有价值的替代方法。     

不同手术方式治疗老年膝内侧间室骨关节炎的疗效对比分析

摘要 目的：比较单踝关节置换术（UKA）和全膝关节置换术（TKA）治疗老年膝内侧间室骨关节炎的疗效。方法：选取2020年1月~2022年6月本院收治的100例老年膝内侧间室骨关节炎患者为研究对象,随机（随机数字表法）分为UKA组（n=50）和TKA组（n=50）,采取相应手术方法治疗。比较两组手术相关指标、美国特种外科医院（HSS）膝关节功能评分、膝关节屈伸活动度（ROM）、疼痛视觉模拟评分法（VAS）、健康调查12条简表（SF-12）评分及假体情况。结果：与TKA组相比,UKA组切口长度更短,术中出血量及术后引流量更少,手术时间、下地行走时间及住院时间更短,组间比较差异均有统计学意义（P<0.05）。UKA组术后2周、3个月及6个月时HSS评分均明显高于TKA组（P<0.05）。UKA组术后2周、3个月ROM均明显高于TKA组（P<0.05）。UKA组术后3个月VAS评分明显低于TKA组（P<0.05）。两组SF-12评分中生理及心理维度评分在术后6个月后均明显提高（P<0.05）;但组间比较差异均无统计学意义（P>0.05）。两组均无假体翻修病例。结论：UKA相比于TKA具有创伤更小、患者术后恢复更快、膝关节功能恢复更好的优势。     

Recovery of walking speed and symmetrical movement of the pelvis and lower extremity joints after unilateral THA

In 17 patients with unilateral hip disease who underwent total hip arthroplasty (THA), the gait was analyzed preoperatively and 1, 3, 6, and 12 months after unilateral THA using a Vicon system to assess the recovery of walking speed and symmetrical movement of the hip, knee, ankle, and pelvis. The walking speed of these patients reached that of normal Japanese persons by 12 months after surgery. Walking speed was correlated with the range of hip motion on the operated side at 1 month postoperatively, and was correlated with the hip joint extension moment of force on both sides from 3 to 6 months after surgery. Before THA, asymmetry was observed in the range of the hip motion, maximum hip flexion, maximum hip extension, maximum knee flexion, as well as in pelvic obliquity, pelvic tilt, and pelvic rotation. There were no differences of the stride length or step length between both sides throughout the observation period. The preoperative range of hip flexion on the operated side during a gait cycle (21.3+/-7.9 degrees ) was significantly smaller than on the non-operated side (46.7+/-7.1 degrees ), and the difference between sides was still significant at 12 months after surgery (35.1+/-6.2 degrees on the operated side and 43.6+/-5.7 degrees on the non-operated side). The majority (74%) of the difference in hip motion range during this period was due to the difference in maximum extension of the hip. The increase in the range of pelvic tilt and the range of motion of the opposite hip showed an inverse correlation with the range of motion of the operated hip, suggesting a compensatory preoperative role. However, this correlation became insignificant after 6 months postoperatively. Asymmetry of the range of hip motion persisted at 12 months after THA in patients with unilateral coxoarthropathy during free level walking, while the operation normalized the spatial asymmetry of other joints and the walking speed prior to the recovery of hip motion.     

Prehabilitation before knee arthroplasty increases postsurgical function: a case study

Conditioning the body to undergo physical stress such as joint arthroplasty has been termed prehabilitation. This case study examined the effect of a 4-week prehabilitation intervention on functional outcomes after total knee arthroplasty (TKA). Two female subjects completed baseline strength and functional assessments before TKA. Subjects were randomized to either a 4-week prehabilitation intervention (ES) aimed at increasing strength and range of motion or a usual care condition (CS). After 4 weeks of training, subjects were reassessed and underwent TKA. Subjects completed a final assessment 12 weeks after TKA. Functional outcomes included 6-minute walk, number of times up from a chair in 30 seconds, proprioception, and self-reported function and pain using the Western Ontario and McMaster Universities Osteoarthritis Index. The data suggest that 4 weeks of prehabilitation had a positive effect on functional task performance and knee proprioception before surgery. After surgery, the ES continued to exhibit higher levels of functioning and less pain compared with the CS. Prehabilitation before TKA may contribute to improved recovery after surgery.     

Effect of severity of knee osteoarthritis on the variability of gait parameters

Gait analysis has provided important information concerning gait patterns and variability of gait in patients with knee osteoarthritis (OA) of varying severity. The objective of this study was to clarify how the variability of gait parameters is influenced by the severity of knee OA. Gait analysis was performed at three different controlled walking speeds in three groups of subjects with varying degrees of knee OA (20 healthy subjects with no OA and 90 patients with moderate or severe OA). The variability of gait parameters was characterized by the coefficient of variance (CV) of spatial-temporal parameters, as well as by the mean coefficient variance (MeanCV) of angular parameters. Based on our results, we conclude that the complexity of gait decreases if the walking speed differs from the self-selected speed. In patients with knee OA, the decreased variability of angular parameters on the affected side represents decreased joint flexibility. This leads to decreased consistency in movements of the lower limbs from stride-to-stride, as shown by increased variability of spatial-temporal parameters. Decreased joint flexibility and consistency of movement can be associated with decreased complexity of movement. Other joints of the kinetic chain, such as joints of the non-affected side and the pelvis, play an important role in compensation and adaptation of step-by step motion and in the ability of secure gait. Results suggest that the variability of gait associated with knee osteoarthritis is gender-dependent. During rehabilitation, particular attention must be paid to improving gait stability and proprioception and gender differences should be taken into account.     

Early strength response of the knee extensors during eight weeks of resistive training after unilateral total knee arthroplasty

The purpose of this study was to document the early history of knee extensor torque production before and after total knee arthroplasty (TKA), explore the relationship between strength assessments, and describe an 8-week resistive-training protocol. Thirty-eight individuals (19 men, 19 women) with unilateral TKA volunteered to participate in this repeated-measures study. For this group, the mean age was 72.23 +/- 5.34 years; height was 168.00 +/- 8.57 cm; and weight was 79.42 +/- 14.57 kg. Torque production of the knee extensors was assessed isokinetically at 60 and 180 degrees .s(-1) before surgery, 30 days after unilateral TKA (+30), and 60 days after unilateral TKA (+60). Torque production was significantly different between limbs at both 60 and 180 degrees .s(-1) (p < 0.0125) before surgery. Torque production was lower at +30 compared with before surgery at both 60 and 180 degrees .s(-1) (p < 0.002). By +60, torque production was greater than at +30 at both 60 and 180 degrees .s(-1) (p < 0.002).     

全膝关节置换术治疗类风湿性关节炎的临床效果分析

目的:探讨全膝关节置换术对类风湿性关节炎的临床疗效。方法:回顾性分析2012年10月至2014年1月在我院接受全膝关节置换术的80例风湿性关节炎患者的临床资料。采用HSS评分标准对膝关节疼痛情况进行评价,根据膝关节活动度(ROM)评价膝关节置换术的临床效果,观察患者术后并发症的发生情况,采用SF-36健康量表评估患者术后的生活质量。结果:患者术后膝关节疼痛评分低于术前(P0.05);患者术后膝关节活动度高于术前,且膝关节伸直和最大屈曲状态均优于术前(P0.05);术后膝关节冠状面和矢状面的畸形率均低于术前,差异具有统计学意义(P0.05);患者术后生存质量明显高于术前,差异具有统计学意义(P0.01)。术后发生感染2例,下肢深静脉血栓3例,膝前区疼痛2例,经对症治疗均获得缓解。结论:全膝关节置换术治疗类风湿性关节炎具有显著的临床效果,值得推广应用。     

Activating the somatosensory system enhances net quadriceps moment during gait

Quadriceps muscle rehabilitation following knee injury or disease is often hampered by pain, proprioception deficits or instability associated with inhibition of quadriceps activation during walking. The cross-modal plasticity of the somatosensory system with common sensory pathways including pain, pressure and vibration offers a novel opportunity to enhance quadriceps function during walking. This study explores the effectiveness of an active knee brace that used intermittent cutaneous vibration during walking to enhance the peak knee flexion moment (KFM) during early stance phase as a surrogate for net quadriceps moment (balance between knee extensor and flexor muscle moments). The stimulus was turned on prior to heel strike and turned off at mid-stance of the gait cycle. Twenty-one subjects with knee pathologies known to inhibit quadriceps function were tested walking under three conditions: control (no brace), a passive brace, and an active brace. Findings show that compared to the control, subjects wearing an active brace during gait exhibited a significant (p < 0.001) increase in peak KFM and no significant difference when wearing a passive brace (p = 0.17). Furthermore, subjects with low KFM and knee flexion angle (KFA) in control exhibited the greatest increase in KFA at loading response in the active brace condition (R = 0.47, p < 0.05). Intermittent cutaneous stimulation during gait, therefore, provides an efficient method for increasing the KFM in patients with knee pathologies. This study’s results suggest that intermittent vibration stimulus can activate the cross-modalities of the somatosensory system in a manner that gates pain stimulus and possibly restores quadriceps function in patients with knee pain.     

Experimentally reduced hip abductor function during walking: Implications for knee joint loads

Hip and knee functions are intimately connected and reduced hip abductor function might play a role in development of knee osteoarthritis (OA) by increasing the external knee adduction moment during walking. The purpose of this study was to test the hypothesis that reduced function of the gluteus medius (GM) muscle would lead to increased external knee adduction moment during level walking in healthy subjects. Reduced GM muscle function was induced experimentally, by means of intramuscular injections of hypertonic saline that produced an intense short-term muscle pain and reduced muscle function. Isotonic saline injections were used as non-painful control. Fifteen healthy subjects performed walking trials at their self-selected walking speed before and immediately after injections, and again after 20 min of rest, to ensure pain recovery. Standard gait analyses were used to calculate three-dimensional trunk and lower extremity joint kinematics and kinetics. Surface electromyography (EMG) of the glutei, quadriceps, and hamstring muscles were also measured. The peak GM EMG activity had temporal concurrence with peaks in frontal plane moments at both hip and knee joints. The EMG activity in the GM muscle was significantly reduced by pain (?39.6%). All other muscles were unaffected. Peaks in the frontal plane hip and knee joint moments were significantly reduced during pain (?6.4% and ?4.2%, respectively). Lateral trunk lean angles and midstance hip joint adduction and knee joint extension angles were reduced by ?1°. Thus, the gait changes were primarily caused by reduced GM function. Walking with impaired GM muscle function due to pain significantly reduced the external knee adduction moment. This study challenge the notion that reduced GM function due to pain would lead to increased loads at the knee joint during level walking.     

Inter-joint coordination of kinematics and kinetics before and after total hip arthroplasty compared to asymptomatic subjects

While differences in joint kinematics and kinetics between control subjects and patients before and after total hip arthroplasty (THA) has often been studied, inter-joint coordination has not been fully characterized. We hypothesized that in patients undergoing THA, inter-joint coordination (i) is different from control subjects before surgery, (ii) changes from pre-operative to post-operative, and (iii) remains different from control subjects after surgery. Seventy-eight subjects underwent gait analysis before and ∼1 year after primary unilateral THA. 109 control subjects were age, sex, and BMI matched to the THA group. We selected a representative trial at each subjects’ self-selected walking speed from a motion analysis data repository. To assess kinematic coordination, we constructed sagittal plane hip-knee angle cyclograms, and calculated total, stance, and swing phase plot area (deg²). To assess kinetic coordination, we calculated the support moment (M_S, %wt 1 ht), the time-integral of support moment (M_S impulse, %wt 1 ht 1 t), and the relative contribution of each joint to M_S impulse (%_Hip, %_Knee, %_Ankle). We used t-tests to compare groups. Total and swing-phase cyclogram area was smaller preoperatively, but improved to control values after THA. Swing-phase area was smaller than control values after THA. M_S impulse was larger in THA subjects than controls both before and after surgery. While, the relative contribution of the hip to M_S impulse was not different from control values, the contributions of the knee and ankle were smaller. Inter-joint coordination, as measured by hip-knee angle cyclograms and M_S impulse, may be used to distinguish differences in gait mechanics between osteoarthritis and THA. Future work focusing on coordination among joints may be needed to fully restore gait function.     

Gait biomechanics in individuals with patellar tendon and hamstring tendon anterior cruciate ligament reconstruction grafts

Anterior cruciate ligament reconstruction (ACLR) restores joint stability following ACL injury but does not attenuate the heightened risk of developing knee osteoarthritis. Additionally, patellar tendon (PT) grafts incur a greater risk of osteoarthritis compared to hamstring grafts (HT). Aberrant gait biomechanics, including greater loading rates (i.e. impulsive loading), are linked to the development of knee osteoarthritis. However, the role of graft selection on walking gait biomechanics linked to osteoarthritis is poorly understood, thus the purpose of this study was to compare walking gait biomechanics between individuals with HT and PT grafts. Ninety-eight (74 PT; 24 HT) subjects with a history of ACLR performed walking gait at a self-selected speed from which the peak vertical ground reaction force (vGRF) during the first 50% of the stance phase and its instantaneous loading rate, peak internal knee extension and valgus moments, and peak knee flexion and varus angles were obtained. When controlling for time since ACLR and quadriceps strength, there were no differences in any kinetic or kinematic variables between graft types. While not significant, 44% of the PT cohort were identified as impulsive loaders (displaying a heelstrike transient in the majority of walking trials) compared to only 25% of the HT cohort (odds ratio = 2.3). This more frequent observation of impulsive loading may contribute to the greater risk of osteoarthritis with PT grafts. Future research is necessary to determine if impulsive loading and small magnitude differences between graft types contribute to osteoarthritis risk when extrapolated over thousands of steps per day.