Co-activation during gait following anterior cruciate ligament reconstruction

BackgroundHeightened co-activation of the quadriceps and hamstrings has been reported following anterior cruciate ligament reconstruction during various tasks, and may contribute to post-traumatic osteoarthritis risk. However, it is unclear if this phenomenon occurs during walking or how co-activation influences gait biomechanics linked to changes in joint health.MethodsCo-activation and gait biomechanics were assessed in 50 individuals with ACLR and 25 healthy controls. Biomechanical outcomes included knee flexion displacement, peak vertical ground reaction force magnitude and rate, peak internal knee extension and valgus moments and rates, sagittal knee stiffness, and the heelstrike transient. Co-activation was calculated for the flexors and extensors collectively (i.e. composite), the medial musculature, and the lateral musculature.FindingsComposite co-activation was greater in the ACLR limb compared to the contralateral limb and the control cohort during the preparatory and heelstrike phases of gait, and co-activation of the medial musculature was greater in the ACLR limb compared to the control cohort during the heelstrike phase. Greater co-activation in multiple gait phases was associated with less knee flexion displacement (r = −0.293 to −0.377), smaller peak vertical ground reaction force magnitude (r = −0.291), smaller peak internal knee extension moment (r = −0.291 to −0.328), and greater peak internal knee valgus moment (r = 0.317).InterpretationIndividuals with ACLR displayed heightened co-activation during walking which was associated with biomechanical outcomes that have been linked to negative changes in joint health following ACLR. These data suggest that excessive co-activation may contribute to the mechanical pathogenesis of post-traumatic osteoarthritis.ClinicalTrials.gov Identifier: NCT02605876.     

间歇性负压干预前交叉韧带重建后的腱一骨愈合

背景;间歇性负压被证实可以促进软组织修复及骨愈合,但其对交叉韧带重建后腱一骨愈合的影响尚未见报道。目的：观察间歇性负压对兔前交叉韧带重建后腱一骨愈合及肌腱移植物生物力学的影响。方法：取24只新西兰大白兔制各自体半腱肌前交叉韧带重建模型,随机取一侧后腿作为负压侧,负压侧关节通过引流管接微型负压吸引器,并维持低强度、间歇性负压;对侧后腿作为对照,接普通引流管。5d后两侧同时拔除吸引管。造模后6周,取关节液检测白细胞介素113的表达水平;取股骨一韧带一胫骨复合体行肌腱移植物拉力测定和腱一骨界面组织学观察。结果与结论：1只兔关节感染,最终23只兔进入结果分析。拉力测定结果显示,负压组完全断裂所需拉力显著大于对照组（P〈0．05）。组织学观察结果发现,负压组成骨细胞数目显著多于对照组,差异有显著性意义（P〈0．01）。关节液检测结果提示负压组关节滑液中自细胞介素113含量低于对照组,差异有显著性意义（P〈0．01）。提示间歇性负压可能在前交叉韧带重建后腱一骨愈合、肌腱移植物的塑性过程中扮演着积极作用。     

前交叉韧带重建后的感染

背景：前交叉韧带重建后感染的发生率比较低,但这种感染会导致灾难性的结果,目前对这种感染的诊断和治疗还没有取得一致的意见。目的：探讨导致前交叉韧带重建术后感染的原因、如何早期诊断,并探讨合适的治疗方案,以尽量保护膝关节的功能。方法：以＂anterior cruciate ligament,reconstruction,infection＂为检索词,检索Pubmed数据库（2007至2012年）;以＂前交叉韧带,重建,感染＂为检索词,检索万方数据库（2007至2012年）。以与前交叉韧带重建后感染的相关文献为评价指标,纳入与前交叉韧带重建后感染相关的内容,排除重复研究。结果与结论：细菌污染手术工具或者韧带移植物是导致前交叉韧带重建后感染的最常见原因,移植物固定的方式和重建后感染之间可能有一定的关系。典型的前交叉韧带重建术后感染的症状和普通的化脓性关节炎的症状类似,但有的前交叉韧带重建后感染的病例并没有感染的典型表现。前交叉韧带重建后感染的诊断需要依靠临床症状、实验室检查（C-反应蛋白和血沉）、膝关节穿刺等方法。大多数外科医师选择静脉使用敏感的抗生素、膝关节灌洗并保留移植物作为自体移植物重建前交叉韧带后感染的首选治疗方法。当感染难以控制或者移植物看起来确实有感染迹象时应该考虑取出移植物。     

Kinematic and kinetic gait deviations in males long after anterior cruciate ligament reconstruction

BackgroundBiomechanical deviations long (approx. 5 years) after anterior cruciate ligament reconstruction have not been quantified in males, despite their distinct risk profile as compared to females. These deviations can indicate altered joint loading during chronic, repetitive motions.MethodsCross-sectional study, comparing kinematic and kinetic variables between 15 male anterior cruciate ligament reconstructed patients and 15 healthy controls. During walking and running gait, measurements were taken of impact dynamics, knee and hip sagittal plane angles and moments, and knee varus angles and adduction moments.FindingsComparing affected limbs to control limbs, significantly lower maximum (P = 0.001) and initial (P = 0.003) loading rates were found during running, but not in walking. Hip angles were lower for affected limbs of patients compared to the control group (P = 0.039) in walking, but not during running. Between-limb comparisons showed important differences in symmetry of the affected patients. Maximum force during running was higher in the unaffected limb (P = 0.015), which was linked with a higher loading rate (P = 0.008). Knee flexion angle was reduced by 2° on average for the affected limb during running (P = 0.010), and both walking and running knee and hip moments showed differences. Knee varus angle showed a 1° difference during walking (P < 0.001), but not during running. Knee adduction moment was significantly lower (more valgus) during both walking and running.InterpretationMale anterior cruciate ligament reconstructed patients demonstrate persistent, clinically important gait asymmetries and differences from healthy controls long after surgery in kinematics, kinetics, and impact biomechanics.     

Lower extremity prism adaptation in individuals with anterior cruciate ligament reconstruction

BackgroundEmerging research has proposed a growing reliance on visual processing during motor performance in individuals following anterior cruciate ligament reconstruction. Reconstructed individuals display increased activation of visual processing areas during task execution and exhibit dramatic performance decrements when vision is completely removed, however the effect of visual information manipulation on performance remains unknown. The purpose of this study was to determine how manipulation of visual information changes performance in persons with anterior cruciate ligament reconstruction.MethodsTwenty-one persons with anterior cruciate ligament reconstruction and 21 matched healthy adults reached to a target with the toe of the involved limb 50 times while wearing prism goggles that vertically shifted their visual field. Toe kinematics were collected to quantify endpoint error and reaching behavior.FindingsStatistical analyses failed to detect significant differences, evidencing both groups performed similarly with respect to endpoint error, movement duration, peak and maximum endpoint velocities, and initial direction error.InterpretationWhen provided inaccurate information via a visual field perturbation, both groups demonstrated comparable adaptation and post-adaptation behavior. These results suggest this sample of persons with anterior cruciate ligament reconstruction are able to effectively integrate information across sensory systems as well as non-injured individuals.     

本体感觉训练在膝前交叉韧带重建术后康复中的应用

目的探讨本体感觉训练在前交叉韧带重建术后康复中的作用。方法将前交叉韧带重建术后患者42例按病区分为本体感觉促进组(26例)和对照组(16例),对照组应用一般康复训练方法,本体感觉促进组应用一般康复训练方法和本体感觉强化训练。术后6个月进行患者位置觉测定、膝关节功能评分及关节稳定性检查。结果在被动角度重现测试中,本体感觉促进组患侧膝的总平均偏差为(4.10±1.38)°,健侧膝的总平均偏差为(3.76±1.93)°,两侧膝比较,差异无统计学意义(P>0.05)。对照组患侧膝的总平均偏差为(4.85±1.55)°,健侧膝的总平均偏差为(3.56±1.72)°,患侧膝的总平均偏差显著大于健侧(P<0.01)。本体感觉促进组的Lysholm评分显著高于对照组(P<0.05)。2组患侧膝Lanchman和Pivotshift检查均为阴性。结论前交叉韧带重建术后应用强化本体感觉训练能促进下肢功能的恢复。     

Gait retraining after anterior cruciate ligament reconstruction

OBJECTIVES: To examine the effects of 2 gait retraining protocols on the gait patterns of patients with bone-patellar tendon-bone anterior cruciate ligament (ACL) reconstruction. DESIGN: Randomized control, repeated-measures design. SETTING: Private orthopedic center and research facility. PARTICIPANTS: Sixteen patients with bone-patellar tendon-bone ACL reconstruction, randomly subdivided into 2 groups (group 1, n=8; group 2, n=8), and a healthy control group of 8 subjects. INTERVENTION: The 16 subjects with ACL reconstruction were randomly assigned to 2 different gait retraining protocols over a 6-week training interval: (1). a protocol using a predicted stride frequency calculated from the resonant frequency of a force-driven harmonic oscillator (FDHO) model or (2). a protocol using the preferred stride frequency (PSF). MAIN OUTCOME MEASURES: Gait analyses examining the lower-extremity kinematic, kinetic, and energetic gait patterns of each group. RESULTS: Gait retraining with the FDHO model showed improvements in lower-extremity positions, hip and knee extensor angular impulse, and work parameters. Gait retraining with the PSF demonstrated no statistical improvements. The FDHO training protocol facilitated a greater midstance knee range of motion (ROM) and greater rates of improvement for midstance ROM, hip extensor angular impulse, and concentric hip extensor work. CONCLUSIONS: Gait retraining with the resonant frequency of an FDHO model facilitated a greater recovery of gait function compared with training with the PSF.     

自体材料重建前交叉韧带术后康复训练

目的:分析近年来关于自体材料重建前交叉韧带术后康复训练的文献资料,了解该领域的发展趋势。资料来源:通过计算机检索Medline1990-01/2005-03的文章,检索词为“anteriorcruciateligament,reconstruction,rehabilitation”,限定文章语言种类为English;另外检索中文期刊全文数据库2000-04/2005-04的文章,检索词为“前交叉韧带、重建术、康复”,文章语言为中文。资料选择:选取有关膝关节前交叉韧带重建术后康复训练的文章,纳入标准:①随机或自身前后对照的临床研究。②观点明确。③采用自体材料重建。排除标准:①综述。②重复性研究。③异体或异种材料重建。资料提炼:共检索到49篇关于膝关节前交叉韧带重建术后康复训练的文章,选择其中符合标准的25篇进行综述。资料综合:观察并比较保守、激进两种不同性质的康复训练方法对术后膝关节功能恢复的影响。一般来说,用骨-髌腱-骨重建后的康复训练应早于用腘绳肌重建,股四头肌肌力训练对术后膝关节功能恢复相当重要,闭链训练适用于康复早期,开链训练适用于康复晚期。由于前交叉韧带中存在着本体感受器,而重建材料中不含有本体感受器,故术后本体感觉促进训练对膝关节功能的完善至关重要。结论:前交叉韧带重建术后的康复训练变得越来越激进。康复训练方案应该按照重建材料的不同及个体差异分别制定。     

自体材料重建前交叉韧带术后康复训练

目的：分析近年来关于自体材料重建前交叉韧带术后康复训练的文献资料，了解该领域的发展趋势。 资料来源：通过计算机检索Medline1990-01／2005-03的文章，检索词为“anterior cruciate ligament，reconstruction，rehabilitation”，限定文章语言种类为English；另外检索中文期刊全文数据库2000-04／2005-04的文章，检索词为“前交叉韧带、重建术、康复”，文章语言为中文。 资料选择：选取有关膝关节前交叉韧带重建术后康复训练的文章，纳入标准：①随机或自身前后对照的临床研究。②观点明确。③采用自体材料重建。排除标准：①综述。②重复性研究。③异体或异种材料重建。 资料提炼：共检索到49篇关于膝关节前交叉韧带重建术后康复训练的文章，选择其中符合标准的25篇进行综述。 资料综合：观察并比较保守、激进两种不同性质的康复训练方法对术后膝关节功能恢复的影响。一般来说，用骨-髌腱-骨重建后的康复训练应早于用膪绳肌重建，股四头肌肌力训练对术后膝关节功能恢复相当重要，闭链训练适用于康复早期，开链训练适用于康复晚期。由于前交叉韧带中存在着本体感受器，而重建材料中不舍有本体感受器，故术后本体感觉促进训练对膝关节功能的完善至关重要。 结论：前交叉韧带重建术后的康复训练变得越来越激进。康复训练方案应该按照重建材料的不同及个体差异分别制定。     

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.     

运动处方在前交叉韧带重建术后患者康复中应用效果的观察

目的探讨运动处方在关节镜下前交叉韧带损伤重建术后患者康复中应用的效果。方法将66例患者随机分为对照组和观察组,每组各33例。对照组患者给予实施常规康复护理,观察组患者在常规康复护理基础上,应用运动处方进行康复训练指导。比较两组患者术后能完成最低强度正面直腿抬高锻炼的时间。结果观察组患者术后能完成最低强度正面直腿抬高时间明显短于对照组,两组比较,差异具有统计学意义(P﹤0.05)。结论 运动处方可有效提高关节镜下前交叉韧带损伤重建术后患者肌力康复的效果,值得临床推广应用。     

Pediatric anterior cruciate ligament reconstruction

An increasing number of anterior cruciate ligament (ACL) injuries are seen in children now than in the past due to increased sports participation. The natural history of ACL deficient knees in active individuals, particularly in children is poor. Surgical management of ACL deficiency in children is complex due to the potential risk of injury to the physis and growth disturbance. Delaying ACL reconstruction until maturity is possible but risks instability episodes and intra-articular damage. Surgical options include physeal-sparing, partial transphyseal and complete transphyseal procedures. This article reviews the management of ACL injured skeletally immature patients including the functional outcome and complications of contemporary surgical techniques.     

The single-leg vertical hop provides unique asymmetry information in individuals after anterior cruciate ligament reconstruction

BackgroundTraditional testing to identify asymmetries after anterior cruciate ligament reconstruction include four similar horizontal hopping tests. The purpose of this study was to determine whether a single-leg vertical hopping test can identify performance and biomechanical asymmetries, and whether performance asymmetries provide unique information compared to traditional tests.MethodsTwelve women with history of anterior cruciate ligament reconstruction [age: 21.1 years (SD 3.2), height: 165.8 cm (SD 6.0), mass: 68.3 kg (SD 8.8)] completed traditional horizontal hop testing. Participants also performed a single-leg vertical hop for maximal height while instrumented for three-dimensional motion analysis. Paired t-tests were performed to identify side-to-side differences in performance variables and Spearman's rank correlations were performed of limb symmetry indices to identify whether the single-leg vertical hop test provides unique information. Repeated measures MANOVAs were performed to identify single-leg vertical hop biomechanical asymmetries.FindingsParticipants exhibited significant side-to-side performance differences during the single-leg vertical hop [mean difference = 0.02 m (SD 0.03), P = .04]. Only weak to moderate relationships were identified between limb symmetry indices of the single-leg vertical hop and other horizontal hopping tests. The vertical hop elicited significant asymmetries of joint kinematics (P = .04) and angular impulse (P = .04). Specifically, the involved limb showed lower peak ankle dorsiflexion (P = .004) and knee abduction (P = .02) angles, lower sagittal plane impulse at the knee (P = .02) and greater sagittal plane impulse at the hip (P = .03).InterpretationThe single-leg vertical hop can identify performance and biomechanical asymmetries in individuals after anterior cruciate ligament reconstruction, potentially providing complementary information to standard horizontal hopping tests.     

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.     

Quadriceps rate of torque development and disability in individuals with anterior cruciate ligament reconstruction

BackgroundThe purpose of this study was to determine associations between self-reported function (International Knee Documentation Committee Index), isometric quadriceps strength and rate of torque development in individuals with a unilateral anterior cruciate ligament reconstruction.MethodsForty-one individuals [31% male, BMI mean 25 (SD 4) kg/m², months post anterior cruciate ligament reconstruction mean 49 (SD 40)] completed the self-reported function and isometric quadriceps function testing. Rate of torque development was assessed at 0–100 ms (early), 100–200 ms (late) ms, and peak following the onset of contraction. Associations were examined between rate of torque development, strength, and self-reported function. Linear regression was used to determine the unique amount of variance explained by the combination of rate of torque development and strength.FindingsHigher rate of torque development 100–200 ms is weakly associated with higher self-reported function in individuals with a unilateral anterior cruciate ligament reconstruction (r = 0.274, p = 0.091); however, rate of torque development 100–200 ms does not predict a significant amount of variance in self-reported function after accounting for strength (ΔR² = 0.003, P = 0.721).InterpretationQuadriceps strength has a greater influence on self-reported function compared to rate of torque development in individuals with an anterior cruciate ligament reconstruction with time from surgery.     

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。     

86例关节镜下前交叉韧带重建术的功能锻炼护理

目的探讨关节镜下前交叉韧带重建术的护理。方法选择因膝关节前交叉韧带损伤住院的患者,根据临床特点,在围术期进行针对性护理措施。结果 86例患者术后均获随访,随访时间3~15个月,平均12个月,Lysholm膝关节评分,膝关节活动度可达0~100°。结论通过严密的观察和采取有效的护理措施,提高了患者的生活质量,减少了并发症发生。     

Pediatric anterior cruciate ligament reconstruction outcomes

Treatment of pediatric anterior cruciate injuries have become an area of controversy sparking much debate about best management strategies. Delaying surgery until skeletal maturity has often been shown to result in unfavorable outcomes due to concomitant meniscal and chondral injuries in this population. There have been numerous techniques used to reconstruct the ACL in the skeletally immature patient; however, most studies are limited by small patient numbers and other methodological concerns. With recent publications reporting failure rates as high as 15–25 % and growth disturbances being uncommon but now reported within almost every technical category, patient and caregiver education become of paramount importance. Key principles will be outlined that may help to avoid some of the pitfalls that occur when dealing with this unique population.     

Graft healing in anterior cruciate ligament reconstruction

Objective

To determine the relationship between lower extremity alignment and MTSS amongst non-professional athletes

Design

In a prospective Study, sixty six subjects were evaluated. Bilateral navicular drop test, Q angle, Achilles angle, tibial angle, intermalleolar and intercondylar distance were measured. In addition, runner's height, body mass, history of previous running injury, running experience was recorded. Runners were followed for 17 weeks to determine occurrence of MTSS.

Results

The overall injury rate for MTSS was 19.7%. The MTSS injury rate in girls (22%) was not significantly different from the rate in boys (14.3%). Most MTSS injuries were induced after 60 hours of exercise, which did not differ between boys and girls. There was a significant difference in right and left navicular drop (ND) in athletes with MTSS. MTSS had no significant correlation with other variables including Quadriceps, Tibia and Achilles angles, intercondylar and intermaleolar lengths and lower extremity lengths.

Limitation

All measurements performed in this study were uniplanar and static. The small sample size deemed our main limitation. The accurate assessment of participants with previous history of anterior leg pain for MTSS was another limitation.

Conclusion

Although a significant relationship between navicular drop and MTSS was found in this study; there was not any significant relationship between lower extremity alignment and MTSS in our sample study.     

Factors informing fear of reinjury after anterior cruciate ligament reconstruction

Objective: Fear of reinjury is associated with cessation of sport after anterior cruciate ligament (ACL) reconstruction despite normal postoperative knee function. The objective of this study is to describe factors informing athletes’ experience of fear of reinjury post ACL reconstruction, in athletes who cited fear as the sole reason for not returning to their pre-injury level of sport. Design: Mixed-methods study design of qualitative and a preliminary quantitative component. Setting: A conveniently selected private hospital. Participants: Ten male and two female athletes, aged between 19 and 45 years, were eligible for the interview from 68 male and 32 female potential participants (age range 17–50) who underwent an ACL reconstruction using any graft type, excluding revision or multi-ligament surgery. Main outcome measures: To explore factors informing fear of reinjury in participants citing fear of reinjury as the sole reason for not returning to sport, albeit normal knee function. Results: From the participant interview, four themes emerged: undergoing the surgery and recovery again, nature of the pre-injury sport imposing risk of reinjury, personality traits, and social priorities. Conclusions: Clinicians should be aware of factors informing fear of reinjury post ACL reconstruction. Modifiable fears including pain, mode and length of rehabilitation and psychological factors should be considered during rehabilitation to potentially improve the return to sport rate.