Alterations in joint kinematics during walking following hamstring and patellar tendon anterior cruciate ligament reconstruction surgery

Background

Previous research has shown that patients with anterior cruciate ligament reconstruction have altered movement patterns in the reconstructed knee during walking. In the sagittal plane, graft specific changes in knee joint motion have been reported between hamstring and patellar tendon anterior cruciate ligament reconstruction grafts. This study examined the secondary planes of movement during walking in anterior cruciate ligament reconstructed knees to evaluate the influences of graft type (hamstring or patellar tendon) and control condition (control group or contralateral knee).

Methods

In 54 participants (18 patellar tendon graft, 18 hamstring graft and 18 controls) varus–valgus and internal–external rotation was measured during level walking in a gait laboratory at mean of 10 months after surgery. All patients had undergone primary unilateral anterior cruciate ligament reconstruction within 12 months of injury.

Findings

For internal–external rotation there was no difference between the graft types and both patient groups had reduced internal rotation (an external rotation offset) and reduced internal rotation range when compared to the control group and contralateral knee. For 31 of 36 patients, internal rotation values were less than the control group mean. The hamstring group had reduced varus rotation compared to both the patellar tendon and control groups, but not when compared to the contralateral knee.

Interpretation

The results show that there are differences in tibial rotation during walking in anterior cruciate ligament reconstructed knees compared to both the contralateral knee and uninjured control group. These kinematic alterations may relate to the high incidence of knee osteoarthritis observed in this population over time. Reduced varus in the hamstring group may relate to the graft harvest.     

适应膝关节肌力变化：是重建前交叉韧带后康复治疗的基本原则

背景：前交叉韧带重建后早期如何干预以减少肌力下降和切取腘绳肌腱后对屈膝肌电-机械延迟的影响是一个值得研究的方向。目的：采用文献分析法重点对前交叉韧带重建后膝关节肌力的变化及康复的进展进行了综述分析。方法：以＂Anterior Cruciate Ligament;hamstring;Muscle Strength＂和＂前交叉韧带;肌力;腘绳肌;电-机械延迟＂为中英文检索词,计算机检索2000年1月至2014年1月PubMed数据库及万方医学网相关文献。选择与前交叉韧带重建后肌力的改变、评价方法及重建后肌力康复相关的文献。最终纳入34篇文献进行探讨。结果与结论：研究表明：切取腘绳肌腱会导致术后的屈膝肌力和胫骨内旋肌力的降低,从而影响膝关节的稳定性和功能活动水平。综合临床和等速肌力测试的结果,可以对前交叉韧带重建后的疗效进行综合评定,H/Q比率（屈/伸比）的改变能够用于指导前交叉韧带损伤后的康复。前交叉韧带重建后移植物塑形过程比其他动物实验研究更长,肌腱松弛度是影响电机械延迟的重要因素之一。在基本康复训练原则的基础上根据个体功能水平及时做出相应的调整,充分体现个性化训练。国内外研究均表明前交叉韧带重建肌力康复始于重建手术之前,以尽早开始肌肉收缩的再训练从而最大程度地防止肌肉萎缩。存在的问题主要集中在康复手段的更细化和科学化以及早期康复训练的＂度＂的把握上。     

Rehabillitation after reconstruction of anterior cruciate ligament with quadrupled-stranded semitendinosus endon and suture plate

Objective To introduce the rehabilitation methods after reconstruction of anterior cruciate ligament(ACL) with quadru-pled-stranded semitendinosus tendon and suture plate.Methods 51cases of ACL ruptures were reconstructed with quadrupled-stranded semi-tendinosus tendon and suture plate,The patients were instructed postoperationally for rehabilitation for more than I year.Results The range of motion of the injured knee were regained in all cases 3 months after operation,The quadriceps/hamstrings peak torque ratio reached approximately 80% of the uninjured leg 1 year after apeation.KT-1000 examination showed that the anterior laxity of the offected knee was greater than the healthy knee in 11.76% and in 10.41% of the patients respectively ,6and 12 months afteroperation,but the patients differences were less than 4 mm,In the other patients ,the anterior laxity of the affected knee was equal or less than the healthy knee 1 year after opation,95.83% patients regain normal gatis,and the total knee score were(97.8&;#177;1.2)according to Lysholm score scale,Conclusion This rehabilitation procedure was practical and effective for functional restoration of the injured knee as well as the injured leg in patients undergoing ACL reconstruction.     

自体四股半腱肌肌腱重建前交叉韧带的功能康复

目的；评价关节镜下用半腱肌肌腱和微型纽扣钢板重建前交叉韧带（ACL）的疗效，并探讨激进康复训练对手术疗效的影响。方法：膝关节前交叉韧带损伤患者32例，均采用关节镜下自体四股半腱肌肌腱和微型纽扣钢板重建ACL，术前后按激进康复方案和本体感觉强化训练。结果：32例患者术后早期均未发生严重并发症。经平均13个月随访，32例患者Lysholm和Gillquist膝关节评分由术前的35-80分提高至78-100分（P〈0．05），其中23例恢复到损伤前运动水平，9例运动水平较前有所下降。结论；关节镜下半腱肌肌腱和微型纽扣钢板重建ACL手术创伤小、出血少，术后恢复快，临床效果满意;配合系统的激进康复训练可明显缩短康复时间，更快地获得膝关节良好的功能。     

前交叉韧带重建失败后的首次翻修

背景：前交叉韧带重建失败可由多种因素引起,需要进行翻修手术治疗。国内关于前交叉韧带翻修的报道较少。目的：分析前交叉韧带重建失败后行翻修治疗的主要原因、适应证、方法及效果。方法：前交叉韧带重建后失稳需要接受翻修患者30例,均在关节镜下行探查与翻修治疗。翻修后应用KT-2000、国际膝关节评分委员会评分标准（IKDC）、Lysholm及Tegner评分系统进行评价。结果与结论：30例患者中,初次手术选用自体骨-髌腱-骨移植物9例,自体半腱股薄肌腱14例,同种异体腘绳肌腱7例,翻修原因上、下两端骨道均偏前8例,上骨道偏前12例,下骨道偏前8例,其中1例合并关节强直;自体骨-髌腱-骨重建固定上骨道内骨块的挤压螺钉位置异常1例;内侧副韧带股骨止点撕脱骨折未予修复1例。翻修术中重建的前交叉韧带完全断裂和吸收12例,韧带有部分连接但已明显松弛失张力18例。无骨道骨质严重缺损,均一期行前交叉韧带翻修手术,重建移植物采用同侧腘绳肌腱（STG）10例,对侧腘绳肌腱14例,人工韧带6例。前交叉韧带翻修后KT-2000检查膝关节屈曲90°和30°平均差值,以及IKDC、Tegner和Lysholm评分均较翻修前有明显改善。前交叉韧带重建手术失败的原因较多,但主要与手术骨道位置异常、固定失效、复合韧带损伤处理不当、关节强直等有关。前交叉韧带翻修后膝关节的主观功能和客观稳定性可获得明显改善。     

经前内侧入路单束4股腘绳肌腱移植重建前交叉韧带

背景:国内外对于经膝关节前内侧入路建立前交叉韧带股骨隧道的临床文献尚缺乏。目的:探讨经膝关节前内侧入路单束4股腘绳肌腱重建前交叉韧带的可行性。方法:65例前交叉韧带损伤患者随机分为两组,其中35例接受经前内侧入路单束4股腘绳肌腱重建前交叉韧带,30例接受经胫骨隧道技术4股腘绳肌腱重建前交叉韧带,重建后平均随访16个月,分别评估膝关节的前向稳定性、旋转稳定性和膝关节的整体功能。结果与结论:最后一次随访时,经胫骨隧道组和经前内侧入路组在Lysholm评分、膝关节前向稳定性方面差异均无显著性意义(P>0.05)。经胫骨隧道组的轴移试验阳性率为23%,经前内侧入路组的阳性率为6%,两组之间差异有显著性意义(P<0.05)。结果可见经膝关节前内侧入路制作股骨隧道重建前交叉韧带,不仅可以重建膝关节的前向稳定性,还可以较好地重建膝关节的旋转稳定性。     

关节镜下四股自体腘绳肌重建膝前交叉韧带的疗效观察

目的探讨关节镜下四股腘绳肌腱治疗膝前交叉韧带损伤的手术方法和疗效。方法对25例前交叉韧带损伤者实施关节镜下四股腘绳肌静力重建。结果随访3—38个月,24例膝关节不稳症状消失,膝活动度0°～112°,平均（107．3±1．24）°。1例术后出现膝内侧疼痛;1例术后患膝伸直型僵直,经关节镜下松解后有效改善。根据Lysholm膝关节评分法,患膝评分由术前（47．71±2．52）分提高到术后（82．35±1．01）分。结论膝前交叉韧带损伤重建应依据患者对关节功能需求和韧带损伤程度酌情选择重建术式,关节镜下自体腘绳肌重建前交叉韧带取材方便,Endo—Button“悬吊”四股胭绳肌腱的长度和强度合理,术后骨一腱愈合程度满足膝关节功能需要。     

The effect of insufficient quadriceps strength on gait after anterior cruciate ligament reconstruction.

OBJECTIVE: To determine the effect of quadriceps strength and joint stability on gait patterns after anterior cruciate ligament injury and reconstruction. DESIGN: Cross-sectional comparative study in which four groups underwent motion analysis with surface electromyography. BACKGROUND: Individuals following anterior cruciate ligament rupture often demonstrate reduced knee angles and moments during the early stance phase of gait. Alterations in gait can neither be ascribed to instability nor to quadriceps weakness alone when both are present. METHODS: Twenty-eight individuals with complete anterior cruciate ligament rupture (10 patients with acute rupture, 8 patients following reconstruction with quadriceps strength >90% of the uninvolved side [strong-anterior cruciate ligament reconstructed group], and 10 patients after reconstruction with quadriceps strength <80% of the uninvolved side [weak-anterior cruciate ligament reconstructed group]), and 10 uninjured subjects underwent an examination of their lower extremity to collect kinematics, kinetics, and electromyography during walking and jogging. Anterior cruciate ligament reconstruction was arthroscopically assisted and a double loop semitendinosis-gracilis autograft or allograft was used as a graft source. All reconstructed subjects had stable knees, full range of motion, and no effusion or pain at the time of testing (more than three months after surgery). RESULTS: Knee angles and moments of the strong group were indistinguishable from the uninjured group during early stance of both walking and jogging. The weak subjects had reduced knee angles and moments during walking, and jogged similarly to the deficient subjects. Regression analysis revealed a significant effect between early stance phase knee angles and moments and quadriceps strength during both walking and jogging. CONCLUSION: Inadequate quadriceps strength contributes to altered gait patterns following anterior cruciate ligament reconstruction. RELEVANCE: Rapid strengthening following anterior cruciate ligament injury or reconstruction may contribute to a safe return to high-level activities.     

采用四股半腱肌肌腱和缝线钢板重建前十字韧带后的康复训练

FromMay１９９７toApril２００１，wereconstructedoldanteriorcruciateligament（ACL）injuryusingquadrupled－strandedsemi－tendinosustendonandsutureplateand１－yearrehabilitationexer－cise，andtherapeuticeffectwasfavorable．Hereisthereport．１Subjectandmethod１．１Subjects５１patients（２７malesand２４femalesaged１３～５７years，meanage：２４．７）enteredourstudy．Patientswithseverecompoundinjuriesofposteriorinnerandouterligamentswereex－cludedfromourstudy．AccordingtoLysholmkneescorescale犤１犦…     

单隧道四股半腱肌股薄肌肌腱重建前交叉韧带后的康复训练

【目的】探讨采用单隧道四股半腱肌股薄肌肌腱重建前交叉韧带后的康复训练方法,总结其近期康复效果。【方法】对49例前交叉韧带断裂的患者采用单隧道四股半腱肌股薄肌肌腱进行重建,术后进行1年以上系统的康复指导。包括支具制动及肌力、活动度、本体感受器训练和肌肉牵张训练等。观察其可行性和效果。【结果】术后3个月,患者膝关节的活动度均恢复正常。术后12个月,患肢的股四头肌和胭绳肌峰力矩比值超过正常侧的82％。术后6个月,膝关节Lanchman试验和轴移试验均为阴性。术后6个月,膝关节功能评分为与术前相比差异有显著性（P〈0．01）。【结论】对于前交叉韧带损伤患者,在采用单隧道四股半腱肌股薄肌肌腱进行重建后进行此康复训练是安全有效的。     

Retraining between months 4 and 6 after anterior cruciate ligament reconstruction with hamstring graft: comparison between cycling and running with an untrained operated subject group]

OBJECTIVE: To study the effect of cycling or running retraining between 4 and 6 months after patients underwent anterior cruciate ligament reconstruction with hamstring grafting (Semitendinosus-Gracilis) compared with that in patients who had the same surgery but were untrained. METHOD: Patients who had undergone surgery for an anterior cruciate ligament reconstruction by the same surgeon who used hamstring grafting were included if they were free of knee pain 4 months after the surgery. After giving consent, patients were randomized to receive controlled retraining (cycling or running 3 times a week) or not. The effect of retraining was measured by the evolution of the knee isokinetic peak torque at 60 degrees/s and 180 degrees/s 6 months after surgery. RESULTS: Fifteen patients were retrained with cycling (GI), 17 with running (GII) and 15 patients did not retrain (GIII). Before retraining, the 3 groups had the same peak torque deficit, measured at an angular speed of 60 degrees/s and 180 degrees/s, for knee extensors (GI: 33+/-11% and 27+/-8%; GII: 30+/-13% and 24+/-10%; GIII: 31+/-15% and 24+/-13%, respectively) and knee flexors (GI: 26+/-11% and 20+/-13%; GII: 20+/-14% and 17+/-13%; GIII: 19+/-15% and 14+/-15%, respectively). After retraining, progress measured at 60 degrees /s of knee extensors and flexors on the operated knees was 18+/-9% and 16+/-10% for GI, 16+/-9% and 11+/-11% for GII and 12+/-15% and 8+/-12 for GIII, respectively. Progress measured at 180 degrees /s followed the same evolution. After comparison of the 3 groups, any significant difference was put in relief according to the type of retraining. CONCLUSION: Retraining after anterior cruciate ligament reconstruction is necessary for patients to practice their previous sport. In our study, aerobic cycling or running between 4 and 6 months after surgery did not improve peak torque in the operated knee extensors and flexors. However, these 2 types of retraining are well-tolerated.     

Is There a Potential Relationship Between Prior Hamstring Strain Injury and Increased Risk for Future Anterior Cruciate Ligament Injury?

Hamstring strain injuries (HSIs) are the most prevalent injury in a number of sports, and while anterior cruciate ligament (ACL) injuries are less common, they are far more severe and have long-term implications, such as an increased risk of developing osteoarthritis later in life. Given the high incidence and severity of these injuries, they are key targets of injury preventive programs in elite sport. Evidence has shown that a previous severe knee injury (including ACL injury) increases the risk of HSI; however, whether the functional deficits that occur after HSI result in an increased risk of ACL injury has yet to be considered. In this clinical commentary, we present evidence that suggests that the link between previous HSI and increased risk of ACL injury requires further investigation by drawing parallels between deficits in hamstring function after HSI and in women athletes, who are more prone to ACL injury than men athletes. Comparisons between the neuromuscular function of the male and female hamstring has shown that women display lower hamstring-to-quadriceps strength ratios during isokinetic knee flexion and extension, increased activation of the quadriceps compared with the hamstrings during a stop-jump landing task, a greater time required to reach maximal isokinetic hamstring torque, and lower integrated myoelectrical hamstring activity during a sidestep cutting maneuver. Somewhat similarly, in athletes with a history of HSI, the previously injured limb, compared with the uninjured limb, displays lower eccentric knee flexor strength, a lower hamstrings-to-quadriceps strength ratio, lower voluntary myoelectrical activity during maximal knee flexor eccentric contraction, a lower knee flexor eccentric rate of torque development, and lower voluntary myoelectrical activity during the initial portion of eccentric contraction. Given that the medial and lateral hamstrings have different actions at the knee joint in the coronal plane, which hamstring head is previously injured might also be expected to influence the likelihood of future ACL. Whether the deficits in function after HSI, as seen in laboratory-based studies, translate to deficits in hamstring function during typical injurious tasks for ACL injury has yet to be determined but should be a consideration for future work.     

关节镜下前交叉韧带重建的术后康复

目的探讨关节镜下自体半腱肌、股薄肌肌腱双束重建前交叉韧带手术的康复治疗方法。方法前交叉韧带断裂病人46例,关节镜下重建前交叉韧带,术后给予系统康复治疗,应用等速测评指导训练,锻炼采取循序渐进的方式实施,并采用LYSHOLM评分标准进行膝关节功能评分。结果 46例中43例恢复正常的关节活动度,LANCHMAN前抽屈试验均转为阴性,LYSHOLM评分优良率为91.3%,等速肌力测试术后峰力矩较术前平均提高35%。结论恰当的术后康复治疗能安全、有效地促进前交叉韧带重建术后患肢的功能恢复。     

Tibial rotation in anterior cruciate ligament reconstructed knees during single limb hop and drop landings

Background

Alterations in knee joint kinematics have been suggested as a potential mechanism that influences the development of osteoarthritis of the knee after anterior cruciate ligament reconstruction. Whilst previous work has shown changes in internal–external tibial rotation during level walking, many patients aim to return to high impact activities following surgery. This study examined tibial rotation during single limb hop and drop landings in anterior cruciate ligament reconstructed knees compared to a control group, and also evaluated the influence of graft type (hamstring or patellar tendon).

Methods

In 48 participants (17 patellar tendon graft, 18 hamstring graft and 13 controls) internal–external rotation was measured during single limb hop and drop landings in a gait laboratory at mean of 10 months after surgery.

Findings

There was no difference between the two graft types and both patient groups had less internal rotation when compared to the control group. For 60% of patients, internal rotation values were at least 5°  less than the control group mean.

Interpretation

Anterior cruciate ligament reconstructed knees with both hamstring tendon and patellar tendon grafts show altered rotational kinematic patterns during high impact dynamic load activities.     

Neuromuscular function in anterior cruciate ligament reconstructed patients at long-term follow-up

BackgroundThe permanence of neuromuscular adaptations following anterior cruciate ligament reconstruction is not known. The aim of this study was to compare bilateral muscle co-contraction indices, time to peak ground reaction force, and timing of muscle onset between anterior cruciate ligament reconstruction subjects 10–15 years post reconstruction with those of matched uninjured controls during a one-leg hop landing.MethodsNine healthy controls and 9 reconstruction subjects were recruited. Clinical and functional knee exams were administered. Lower limb co-contraction indices, time to peak ground reaction force, and muscle onset times were measured bilaterally. Differences in clinical and functional outcomes were assessed with unpaired t-tests, and mixed model repeated measures were used to examine effects of group, limb and interaction terms in electromyography measures.Findings89% of control knees were clinically “normal”, whereas only 33% of reconstructed knees were “normal”. Anterior cruciate ligament-reconstructed subjects tended to achieve shorter functional hop distances but demonstrated symmetrical lower limb electromyography measures that were no different from those of controls' with the exception that biceps femoris activation was delayed bilaterally prior to ground contact but was greater during the injury risk phase of landing.InterpretationWith the exception of hamstring activation, lower limb electromyography measures were largely similar between ligament-reconstructed and matched control subjects, which was in contrast to the clinical findings. This result brings into question the significance of neuromuscular function at this long-term follow-up but raises new questions regarding the role of symmetry and pre-injury risk.     

Vorderes Kreuzband—was ist gesichert?

A rupture of the anterior cruciate ligament causes a pathological anterior translation and an increased internal rotation of the tibia. Subjective symptoms are instability and a decreased activity level. The pathological motion pattern of the knee results in a high incidence of secondary meniscus and chondral damage. The natural history is mainly dependent on the activity level of the subject. Indications for operative reconstruction are young age, high activity and complex ligament injuries of the knee. The anterior cruciate ligament can be reconstructed by an autologous tendon graft. Patellar tendon, hamstring tendon and quadriceps tendon grafts can be used. There are no systematic differences between the outcome related to these grafts. The procedure can be performed arthroscopically or using a mini-open technique with equal result. Main success factors are an anatomical placement of the graft with stable fixation, avoidance of impingement in the intercondylar notch and adequate pretension. Optimum time periods for surgery are the first 48 h after the injury and the secondary phase when the initial inflammation has subsided and the range of motion is free. The rehabilitation must be tailored to the initial mechanical strength of the graft fixation. Preventive training has been proven to be effective to reduce the incidence of anterior cruciate ligament ruptures in handball and soccer players and should be used more widely.     

自体与同种异体肌腱重建膝关节前交叉韧带的比较

背景:关节镜辅助下重建前交叉韧带的移植物主要有自体移植物、同种异体移植物和人工韧带3种,关于移植物的选择,存在较多争议。目的:评估自体健侧腘绳肌腱和同种异体肌腱两种移植物在膝关节前交叉韧带重建中的效果。方法:纳入2007-01/2009-01在承德医学院附属医院骨科就诊的经关节镜检查证实为前交叉韧带损伤的患者70例(70膝),分别采用自体健侧腘绳肌腱和同种异体肌腱重建前交叉韧带,记录膝关节Lysholm功能评分、KT-1000测量值及不良反应。结果与结论:患者随访18~24个月,均未发生血管神经损伤,无感染、植入物断裂等并发症;同种异体肌腱移植患者有2例膝关节引流管口持续渗出,经换药半月后愈合,其余切口均一期愈合。末次随访时,自体健侧腘绳肌腱和同种异体肌腱重建患者的Lysholm评分均显著提高,双侧膝关节前向松弛度差值显著减少,且两种方法比较差异无显著性意义(P>0.05)。说明应用自体健侧腘绳肌腱与同种异体肌腱重建膝关节前交叉韧带疗效相当,效果满意。     

Proprioceptive and behavior impairments in individuals with anterior cruciate ligament reconstructed knees

OBJECTIVE: To assess sensory deficits and their effects on proprioceptive and motor function in patients who had undergone unilateral anterior cruciate ligament (ACL) reconstruction. DESIGN: Four evaluations were conducted: (1) joint position perception of the knee for predetermined angles (0 degrees, 15 degrees, 30 degrees, 45 degrees, 60 degrees ); (2) threshold for detection of passive knee motion at 0 degrees, 15 degrees, 30 degrees, 45 degrees, and 60 degrees moving into flexion and at 15 degrees, 30 degrees, 45 degrees, and 60 degrees moving into extension; (3) latency onset of hamstring muscles; and (4) postural control during upright double- and single-leg stance. SETTING: Movement laboratory in Brazil. PARTICIPANTS: Ten participants who had surgical reconstruction of the ACL (reconstructed group) and 10 participants without knee injury (control group). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Absolute error, angular displacement, hamstring muscles latency, and mean sway amplitude. RESULTS: Individuals with a reconstructed knee showed decreased joint position perception, a higher threshold for detection of passive knee motion, longer latency of hamstring muscles, and decreased performance in postural control. CONCLUSIONS: After lesion and ACL reconstruction, sensory and motor behavior changes were still observed. This may be because of the lack of proprioceptive information resulting from the ACL lesion and/or substitution of ACL by the graft.     

关节滑液对兔前交叉韧带重建后腱骨愈合生物力学和组织学的影响

背景:目前前交叉韧带重建后关节滑液对移植物强度以及腱骨愈合的影响尚无定论。目的:观察兔前交叉韧带重建后腱骨愈合过程中,关节滑液对移植肌腱生物力学及组织学的影响。方法:取新西兰大白兔下肢半腱肌腱,以同侧肢体半腱肌腱重建前交叉韧带模拟关节滑液影响模型,并同时取对侧肢体半腱肌行股骨髁上"U"形肌腱埋植避免关节滑液的影响。重建4周,取股骨-韧带-胫骨复合体,行生物力学测定和组织学观察。结果与结论:重建后4周,生物力学测定时发现"U"字形埋植肌腱断裂时平均载荷明显大于前交叉韧带重建后处于关节内的肌腱(P<0.01)。组织学观察发现,骨隧道内坏死的腱组织已被纤维组织、新生骨组织替代,腱骨交界面形成Sharpey纤维连接和纤维软骨,优于关节内肌腱;"U"字形埋植肌腱腱骨交界面成骨细胞数目明显多于前交叉韧带重建肌腱(P<0.01)。结果证实"U"字形埋植肌腱的生物力学及腱骨愈合均优于处于关节内肌腱,提示关节滑液对前交叉韧带重建后韧带的强度以及腱骨愈合有不利影响。     

Bilateral kinematic and kinetic analysis of the squat exercise after anterior cruciate ligament reconstruction

OBJECTIVES: To characterize the bilateral lower-extremity kinematics and kinetics associated with squatting exercise after anterior cruciate ligament (ACL) reconstruction. DESIGN: We evaluated bilaterally sagittal plane kinematics and kinetics of the ankle, knee, and hip joints during submaximal squatting exercise in rehabilitating patients after ACL reconstruction. Comparisons were performed between involved and noninvolved limbs, and regression models were created to examine the relations between the bilateral kinetic differences and time postsurgery. SETTING: A motion analysis laboratory. PARTICIPANTS: Eight adults (27.9+/-6.8y) with unilateral ACL reconstruction (postsurgical time, 30+/-12wk). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Sagittal plane ankle, knee, and hip peak net moments of force, maximum joint excursion angles, and peak vertical ground reaction forces. RESULTS: Peak vertical ground reaction forces did not differ between limbs. The peak knee extensor moment generated during the submaximal squatting exercise was 25.5% greater in the noninvolved limb than in the involved limb (P=.003). The peak ankle plantarflexor moment did not differ between limbs (P=.85); however, there was a trend toward a greater hip extensor moment in the involved limb (P=.06). The ratio of the peak hip extensor moment to the peak knee extensor moment was 46.5% greater in the involved limb (P=.02). Only the peak dorsiflexion angle differed between limbs (P=.02). None of the linear models examining the relations between differences in the involved limb and noninvolved limb kinetics, and postsurgical time, were statistically significant. CONCLUSIONS: Patients performing the squat exercise, within 1 year of ACL reconstructive surgery, used 2 strategies for generating the joint torques required to perform the movement: (1) in the noninvolved limb, patients used a strategy that equally distributed the muscular effort between the hip and knee extensors, and (2) in the involved limb, patients used a strategy that increased the muscular effort at the hip and reduced the effort at the knee. These intra- and interlimb motor-programming alterations (ie, substitution strategies) could potentially slow or limit rehabilitation, and induce strength and performance deficits.