The effect of hip adduction angle on patellar position measured using real time ultrasound scanning

IntroductionThere are limited in vivo studies investigating the influence of the Iliotibial Band (ITB) on patellar position, despite numerous references in the literature to this relationship. The purpose of this study was to investigate how the ITB influences patellar position, in vivo, indirectly through alteration of frontal plane hip position.MethodTwelve healthy, asymptomatic, male subjects (age 23 ± 2.6 years) had their patellar position examined using real time ultrasound scanning. The knee was passively placed into 20° flexion and combined with hip neutral, 20° hip adduction and 20° hip abduction. Mean patellar position (distance from the lateral border of the patella to the edge of the intersection of the trochlear groove and lateral femoral condyle) was measured, with the smaller values representing a position whereby the patella is drawn more laterally and closer to the lateral femoral condyle.ResultsMean patellar position for neutral was 8.1 mm (± 1.72 mm). Following 20° hip abduction the mean patellar position was 8.9 mm (± 1.79 mm), this was a statistically significant change in patellar position (p = 0.003). Following 20° hip adduction the mean patellar displacement was 7.3 mm (± 1.4 mm) which, again, was a statistically significant change in patellar position (p = 0.009). The results indicate that with the hip adduction the patella was positioned significantly more laterally (smaller value for distance).DiscussionThe results of this study support the hypothesis that hip adduction which is likely to create loading and lengthening of the ITB causes significantly greater lateral displacement of the patella, than when the hip is abducted and the ITB unloaded.Level of evidence: 2b individual cohort study.     

The relationship between length of the iliotibial band and patellar position in Asians

BackgroundTightness of the iliotibial band (ITB) has been documented as a major factor in lateral patellar translation because the ITB inserts into the lateral border of the patella through the iliopatellar band. The aim of this study was to compare the patella–condyle distance (PCD) between subjects with and without ITB tightness. We also investigated the relationship between ITB length and lateral patellar translation in hip adduction.MethodsIn 40 healthy volunteers, we measured the ITB length with Ober's test and the PCD at two hip positions (neutral and 20° adduction) using ultrasonography. Lateral patellar translation in hip adduction was calculated by subtracting the PCD at the adduction position from the hip neutral position.ResultsTwenty-three of the 40 subjects had ITB tightness; these subjects had a significantly laterally positioned patella at 20° adduction of the hip (p = 0.044). Patients with ITB tightness also had greater lateral patellar translation in hip adduction than patients without tightness (p = 0.000). The ITB length was moderately correlated with the PCD at 20° adduction of the hip (r = 0.427, p = 0.042) and strongly negatively correlated with lateral patellar translation (r = − 0.717, p < 0.000).ConclusionsThese findings support the hypothesis that increasing ITB tension has a significant effect on the position of the patella and therefore affects translation of the patella. However, these findings do not indicate that ITB length is the only cause of lateral patellar translation; further studies are needed to assess the relative importance of different factors that could affect patellar position.     

Gait deviations and muscle strength deficits in subjects with patellar instability

BackgroundAbnormal tracking of the patella is a hallmark sign of patellar instability (PI). Gait deviations and strength deficits may exacerbate abnormal tracking. The identification of modifiable gait deviations and strength deficits can aid in developing more effective management strategies for individuals with PI. The purpose of this study was to identify modifiable gait and strength deficits in subjects with PI.Methods32 subjects (16 PI, 16 controls, 3 males/13 females in each group, 21.1 years old, 23.5 BMI), performed an instrumented gait analysis while walking at 1.5 m per second. Subjects' peak hip adduction angles, external rotation angles, hip abduction moments, knee flexion angles, knee adduction angles, and knee extensor moments were measured during walking. Hip abduction, hip external rotation, and knee extension strength were assessed with a handheld dynamometer.ResultsIndividuals with PI displayed significantly lower peak knee adduction angles (1.8 ± 2.8° PI, 5.5 ± 4.5° control, p < .01) and peak hip abduction moments (0.2 ± 0.1 Nm/kg*m PI, 0.4 ± 0.1 Nm/kg*m control, p < .01). Subjects with PI were weaker in knee extension strength (14.5 ± 4.1 kg/m PI, 23.8 ± 7.2 kg/m control, p < .01), hip abduction strength (12.1 ± 2.0 kg/m PI, 17.8 ± 4.0 kg/m control, p < .01), and hip external rotation strength (5.5 ± 1.9 kg/m PI, 7.1 ± 1.3 kg/m control, p = .01).ConclusionSubjects with patellar instability have smaller joint moments and a more valgus knee position while walking. Coupled with deficits in muscle strength, this likely contributes to subjective reports of chronic patellar instability.Level of Evidence.III     

Combined medial and lateral patellar retinaculum plasty for skeletally immature patients with patellar dislocation and low-grade trochlear dysplasia

BackgroundTo evaluate the clinical outcomes of combined medial and lateral patellar retinaculum plasty for skeletally immature patients with patellar dislocation and low-grade trochlear dysplasia.MethodsFrom December 2014 to December 2016, we reviewed 19 skeletally immature patients who underwent medial and lateral patellar retinaculum plasty at our institution. Clinical evaluations were performed pre- and postoperatively, and included determination of the number of patellar re-dislocation patients, the Kujala and Tegner scores, the patellar tilt angle, lateral patellar shift, and congruence angle. The radiographic evaluation parameters were measured on computed tomography scans.ResultsNo dislocation or subluxation occurred during the mean follow-up of 35.42 months (24–48 months). Postoperatively, the Kujala score improved from 57.6 ± 4.2 to 86.9 ± 8.1 (P < 0.05), and the Tegner activity score improved from 2.6 ± 1.0 to 5.0 ± 1.3 (P < 0.05). Radiographically, the patellar tilt angle decreased from 32.7 ± 5.9° to 13.4 ± 4.28° (P < 0.05), the lateral patellar shift decreased from 15.9 ± 1.1 mm to 8.4 ± 0.6 mm (P < 0.05), and the congruence angle decreased from 29.9 ± 15.3° to − 9.6 ± 15.5° (P < 0.05).ConclusionsMedial and lateral patellar retinaculum plasty is a promising procedure that has the advantage of being a simple operation that induces little trauma. It is a good treatment option for skeletally immature patients with patellar dislocation who have low-grade trochlear dysplasia.     

Lateral patellar maltracking due to trochlear dysplasia: A computational study

BackgroundThe study focuses on the influence of trochlear dysplasia on patellar tracking related to patellar instability.MethodsKnee extension against gravity and dual-limb squatting were simulated with seven models representing knees being treated for recurrent instability. Trochlear depth was altered to represent lateral trochlear inclination (LTI) values of 6°, 12° and 24°. Repeated measures analyses compared patellar lateral shift (bisect offset index) across different LTI values. Peak bisect offset index during extension and squatting was correlated with patella alta (Caton–Deschamps index) and maximum lateral position of the tibial tuberosity.ResultsBisect offset index varied significantly (p < 0.05) between different LTI values at multiple flexion angles throughout simulated knee extension and squatting. Average bisect offset values were 1.02, 0.95, and 0.86 for LTI = 6°, 12°, and 24°, respectively, at 0° of flexion for knee extension. The strongest correlation occurred between peak bisect offset index and lateral position of the tibial tuberosity for knee squatting with LTI = 6° (r² = 0.81, p = 0.006). The strength of the correlation decreased as LTI increased. Caton–Deschamps was only significantly correlated with patellar tracking for LTI = 24° during knee squatting.ConclusionsA shallow trochlear groove increases lateral patellar maltracking. A lateral tibial tuberosity in combination with trochlear dysplasia increases lateral patellar tracking and the risk of patellar instability. Patella alta has relatively little influence on patellar tracking in combination with trochlear dysplasia due to the limited articular constraint provided by the trochlear groove.     

Three-dimensional assessment of lower limb alignment: Reference values and sex-related differences

BackgroundThree-dimensional (3D) preoperative planning and assisted surgery is increasingly popular in deformity surgery and arthroplasty. Reference ranges for 3D lower limb alignment are needed as a prerequisite for standardized analysis of alignment and preoperative planning in 3D, but are not yet established.MethodsOn 60 3D bone models of the lower limbs based on computed tomography data, fifteen parameters per leg were assessed by standardized validated 3D analysis. Distribution parameters and differences between sexes were evaluated. Reference values were generated by adding/subtracting one standard deviation from the mean.ResultsWomen had a significantly lower mean mechanical lateral distal femoral angle compared with men (86.4 ± 2.1° vs. 87.8 ± 2.0°; P < .05) and significantly lower mean joint line convergence angle (−2.5 ± 1.4° vs. -1.3 ± 1.2; P < .01), but higher mean hip knee ankle angle (178.9 ± 1.9° vs. 177.8 ± 2.3°; P < .05) and mean femoral torsion (18.2 ± 9.5° vs. 13.2 ± 6.4°; P < .05), resulting in a tendency towards valgus alignment and vice versa for men. Differences in mean medial proximal tibial angle were not significant. The mean mechanical axis deviation from the tibial knee joint center was 6.9 ± 7.3 mm medial and 1.4 ± 16.1 mm ventral without significant differences between sexes.ConclusionsWe describe total and sex-related reference ranges for all alignment relevant axes and joint angles of the lower limb. There are sex-related differences in certain alignment parameters, which should be considered in analysis and surgical planning.     

A comparison of tibiofemoral and patellofemoral alignment during a neutral and valgus single leg squat: an MRI study

BackgroundThe etiology of anterior knee pain is not well understood. Recently, excessive hip adduction and internal rotation have been cited as possible factors. However, how these altered hip mechanics affect the patellofemoral joint is still unclear.ObjectiveTo compare the three-dimensional tibiofemoral and patellofemoral alignment between a neutral squat and one performed with increased hip adduction and internal rotation. We aimed to examine the relationships between the three-dimensional tibiofemoral and patellofemoral alignment during a neutral and valgus squat. Finally, we aimed to determine the relationship between two-dimensional and three-dimensional measures of patellofemoral alignment.Methods10 healthy subjects were recruited for this study. Knee and patellar kinematics in a neutral squat and one performed with hip adduction and internal rotation were measured using a open, upright, magnetic resonance imaging unit. Both single leg squats were performed at 30° of knee flexion.ResultsThere was a significant correlation between knee external rotation and lateral patellar translation, and between knee abduction and lateral patellar translation. Moderate relationships were found between the 2D and 3D measures but these were not statistically significant.ConclusionThe valgus squat resulted in greater knee external rotation in all subjects. Although mean patellar mechanics were not different in the valgus squat, lateral patellar translation increased as knee external rotation increased. Lastly, 2D measures of patellofemoral alignment only provide moderately fair surrogates for 3D measures.     

Anteroposterior distance between the tibial tuberosity and trochlear groove in patients with patellar instability

BackgroundOur objective was to describe a measurement to assess sagittal tibial tuberosity (TT)–trochlear groove (TG) distance and to compare this between asymptomatic (control) patients and patients with symptomatic patellar instability.MethodsWe compared static CT images of 22 fully extended knees of patients with symptomatic patellar instability with images of 22 asymptomatic knees. TT–TG distance was measured to quantify lateralization of the TT, and anteroposterior TT–TG distance was used to quantify the sagittal distance between these two points. Lateral trochlear inclination, sulcus angle, and trochlear depth were measured. Groups were compared using paired t tests (alpha = 0.05). Correlations of anteroposterior TT–TG distance with lateral trochlear inclination, sulcus angle, and trochlear depth were assessed using linear and multivariate regression.ResultsMean TT–TG distances were 19.9 ± 4.4 mm (symptomatic) and 16.8 ± 5.5 mm (control) (mean ± std deviation) (P = 0.002). Mean anteroposterior TT–TG distances were 8.3 ± 7.8 mm (symptomatic) and ? 0.5 ± 4.6 mm (control) (P < 0.0001). The symptomatic group had greater measurements of trochlear dysplasia, with lower lateral trochlear inclination, greater sulcus angle, and lower trochlear depth (all P < 0.0001). Anteroposterior TT–TG distance and trochlear depth were strongly negatively correlated (r = 0.62, R² = 0.39, P < 0.0001).ConclusionsIn asymptomatic patients, the anteroposterior TT–TG distance was ? 0.5 mm, indicating that the TG and TT were nearly in the same coronal plane. In patients with symptomatic patellar instability, the TG was almost nine millimeters anterior, and this distance correlated with measurements of trochlear dysplasia.Level of evidenceIII, case control study.     

Quadriceps muscle compensatory activations are delayed following anterior cruciate ligament reconstruction using hamstring tendon graft

BackgroundCompensatory and anticipatory quadriceps activation (CQA and AQA) in response to postural perturbations are essential for functional stability of the knee. This study aimed at investigating CQA and AQA before and after anterior cruciate ligament reconstruction (ACLR) using hamstrings graft.MethodsTwelve participants with ACLR and 12 healthy controls were exposed to 10 either unpredictable or predictable perturbations of the knee before ACLR (T1), two months (T2) and six months (T3) after surgery. Latencies of CQA and AQA in vastus lateralis (VL), rectus femoris (RF) and vastus medialis (VM) were measured.ResultsLatency of CQA was delayed in ACLR compared to controls at T1 for VL (105 ± 25 vs. 57 ± 9 ms; P < .001), RF (102 ± 23 vs. 56 ± 9 ms; P < .001) and VM (107 ± 24 vs. 66 ± 16 ms; P < .001), at T2 for VL (68 ± 14 vs. 55 ± 10 ms; P < .01) and at T3 for VL (105 ± 22 vs. 58 ± 7 ms; P < .001), RF (102 ± 22 vs. 58 ± 12 ms; P < .001) and VM (106 ± 20 vs. 63 ± 8 ms; P < .001). AQA occurred earlier in ACLR than in controls at T1 for VL (− 82 ± 64 vs. − 14 ± 11 ms; P < .05) and VM (− 105 ± 68 vs. -9 ± 12 ms; P < .05).ConclusionCQA are delayed following ACLR with hamstring graft and should be addressd by post-surgical rehabilitation.     

Tibial tubercle proximalization as quadriceps lengthening in treating severe habitual patellar dislocation in adults

BackgroundTo describe a novel ‘four-in-one’ procedure – including tibial tubercle proximalization, extensive lateral release, tibial tubercle medialization, and medial patellofemoral ligament reconstruction – for treating severe habitual patellar dislocation (HPD) in adults, and to report its early clinical outcomes.MethodsThirteen patients (13 knees) with severe primary HPD received this procedure. Results of the physical examinations, including apprehension tests and patellar tracking throughout full range of motion, were recorded pre-operatively and at final follow-up. Radiological assessments included standard anteroposterior view, true lateral view at 30° knee flexion, axial views of the patellofemoral joint at both 30° and maximum angle of knee flexion, and computed tomography scans at full knee extension pre-operatively and at final follow-up. Subjective patellofemoral functions were evaluated with the Kujala functional score before the index procedure and at final follow-up visit.ResultsAll 13 patients were followed for an average period of 35.5 months (range, 25–49). After the index ‘four-in-one’ procedure no patient reported reoccurrence of patellar dislocation at the final follow-up visit. Radiographically, there was a statistically significant improvement in the congruence angle from 75.2 ± 16.3° pre-operatively to ? 7.2 ± 5.4° postoperatively (P < 0.01) and in the lateral patellofemoral angle from ? 66.3 ± 8.3° pre-operatively to 6.3 ± 2.6° postoperatively (P < 0.01). The average pre-operative Kujala functional score was 41.4 and average postoperative score was 94.9 (P < 0.05).ConclusionThe novel ‘four-in-one’ procedure effectively treated HPD in adults with severe quadriceps contracture.     

斜外侧腰椎融合术联合Smith-Petersen截骨治疗伴矢状面失衡成人退行性脊柱侧凸疗效观察

目的 观察斜外侧腰椎椎间融合术（oblique lumbar interbody fusion, OLIF）联合Smith-Petersen截骨（SPO截骨）对成人退行性脊柱侧凸矢状面失衡矫形效果,并与单纯后路矫形融合手术进行比较。方法 回顾性分析2014年11月至2019年10月华中科技大学同济医学院附属同济医院收治的64例成人退行性脊柱侧凸患者资料,根据手术方式分为OLIF联合SPO组（33例）和单纯后路矫形组（31例）。记录患者的手术时间、术中出血量及术后住院时间;评估术前、术后3个月、术后1年及末次随访的腰痛和腿痛的疼痛视觉模拟评分（visual analogue scale, VAS）、Oswestry功能障碍指数（Oswestry disability index, ODI）;脊柱全长X线评估脊柱侧凸冠状面Cobb角、腰椎前凸角（lumbar lordosis, LL）、骨盆倾斜角（pelvic tilt, PT）、骨盆入射角（pelvic incidence, PI）与腰椎前凸角（LL）差值（PI-LL）、矢状面平衡（sagittal vertical axis, SVA）等情况,并观察随访期内固定相关并发症,包括近端交界性后凸（proximal junctional kyphosis, PJK）、近端交界区失败（proximal junctional failure, PJF）、内固定失败等。结果 所有患者随访24 ～ 51个月,平均（34.38±8.6）个月。OLIF联合SPO组术中出血量及术后平均住院时间低于单纯后路矫形组（P＜0.05）,而平均手术时间高于单纯后路矫形组（P<0.001）。两组患者术后腰、腿痛VAS评分及ODI评分较术前有显著下降（P＜0.05）,两组间比较差异无统计学意义（P＞0.05）;冠状面参数比较,两组患者术后随访冠状面Cobb角均较术前明显下降,同时OLIF联合SPO组术后及末次随访Cobb角小于单纯后路矫形组（术后1周6.8°±4.5° vs 12.3°±7.3°,末次随访9.1°±7.3° vs 15.2°±11.7°,P＜0.05）。矢状面参数比较,两组术后及末次随访PT、LL、PI-LL及SVA均较术前明显改善（P＜0.05）,而OLIF联合SPO组末次随访LL大于单纯后路矫形组（34.3°±6.4° vs 29.6°±8.9°）,PI-LL小于单纯后路矫形组（16.4°±5.3° vs 21.9°±11.2°）,差异具有统计学意义（P＜0.05）。OLIF联合SPO组PJK、PJF及内固定失败等内固定相关并发症发生率低于单纯后路矫形组（18.2% vs 25.8%）,但差异无统计学意义（P=0.461）。结论 OLIF联合Smith-Petersen截骨治疗成人退变性脊柱侧凸安全、有效,其能够提供坚强的前柱支撑,有效地恢复腰椎前凸,纠正矢状面失衡,并且还有助于减少术中出血,促进术后康复。     

Patellar resurfacing has minimal impact on in vitro tibiofemoral kinematics during deep knee flexion in total knee arthroplasty

BackgroundWhile patellar resurfacing can affect patellofemoral kinematics, the effect on tibiofemoral kinematics is unknown. We hypothesized that patellar resurfacing would affect tibiofemoral kinematics during deep knee flexion due to biomechanical alteration of the extensor mechanism.MethodsWe performed cruciate-retaining TKA in fresh-frozen human cadaveric knees (N = 5) and recorded fluoroscopic kinematics during deep knee flexion before and after the patellar resurfacing. To simulate deep knee flexion, cadaver knees were tested on a dynamic, quadriceps-driven, closed-kinetic chain simulator based on the Oxford knee rig design under loads equivalent to stair climbing. To measure knee kinematics, a 2-dimensional to 3-dimensional fluoroscopic registration technique was used. Component rotation, varus-valgus angle, and anteroposterior translation of medial and lateral contact points of the femoral component relative to the tibial component were calculated over the range of flexion.ResultsThere were no significant differences in femoral component external rotation (before patellar resurfacing: 6.6 ± 2.3°, after patellar resurfacing: 7.2 ± 1.8°, p = 0.36), and less than 1° difference in femorotibial varus-valgus angle between patellar resurfacing and non-resurfacing (p = 0.01). For both conditions, the medial and lateral femorotibial contact points moved posteriorly from 0° to 30° of flexion, but not beyond 30° of flexion. At 10° of flexion, after patellar resurfacing, the medial contact point was more anteriorly located than before patellar resurfacing.ConclusionDespite the potential for alteration of the knee extensor biomechanics, patellar resurfacing had minimal effect on tibiofemoral kinematics. Patellar resurfacing, if performed adequately, is unlikely to affect postoperative knee function.     

Clinical outcomes of medial patellofemoral ligament reconstruction using FiberTape and knotless SwiveLock anchors

BackgroundWe aimed to prospectively investigate the clinical outcomes of medial patellofemoral ligament (MPFL) reconstruction using polyester high-strength suture tape with knotless anchors.MethodForty-three patients (65 knees) were followed for at least 1 year postoperatively, with 27 patients (43 knees) followed for 2 years postoperatively. All patients underwent MPFL reconstruction using polyester high-strength suture tape (FiberTape®; Arthrex) with knotless anchors (SwiveLock®; Arthrex). Repeated dislocation and residual patellar apprehension signs were recorded, and congruence and tilting angles were measured. Changes in Knee Injury and Osteoarthritis Outcome Scale (KOOS) scores and their associations with the preoperative tibial tubercle–trochlear groove (TT-TG) distance were analyzed.ResultsNo repeat dislocations (0%) were observed. One (2.4%) residual positive patellar apprehension sign was noted. The mean tilting angle decreased from 24.8° to 10.7° (P < 0.001), and the mean congruence angle decreased from 24.9° to 4.3° (P < 0.001). At 2 years follow up, all KOOS subscales had improved: pain (92.0 ± 12.9), symptoms (90.2 ± 11.9), activities of daily living (95.7 ± 7.3), sports activity (85.7 ± 16.9), quality of life (87.7 ± 12.9), and patellofemoral (89.0 ± 9.6) outcomes. KOOS subscale scores improved regardless of the preoperative TT-TG distance (21.1 ± 3.5 mm; range, 13.8–29.9 mm).ConclusionsMPFL reconstruction using FiberTape and knotless SwiveLock anchors was performed without sacrificing autologous tissue. No recurrent patellar dislocation was observed during the 2-year follow up period. All KOOS subscale scores improved using FiberTape and SwiveLock anchors in MPFL reconstruction.     

Histopathological study of the infrapatellar fat pad in the rat model of patellar tendinopathy: A basic study

Background

Patellar tendinopathy is difficult to successfully treat. This study aimed to characterize the pathological changes of the infrapatellar fat pad (IPFP) in patellar tendinopathy (PT), and to investigate the influence of PT on the development of fibrotic changes in the IPFP.

Movement and volume of infrapatellar fat pad and knee kinematics during quasi-static knee extension at 30 and 0° flexion in young healthy individuals

IntroductionThe purpose of this study was to determine the changes in the shape and volume of the infrapatellar fat pad (IPFP) associated with knee flexion angle in young healthy individuals.MethodsYoung, healthy individuals without a history of knee injuries participated in this cross-sectional study. Behavior of the IPFP was quantified using three-dimensional (3D) models of the IPFP, patella, patellar tendon, femur, and tibia obtained from MRI taken at 0° and 30° flexion. The outcomes were movement and volume change of the IPFP, movement of the patella and the tibia, and change of the patellar tendon angle and length.ResultsThe anterior surface of the IPFP significantly moved anteriorly by 5.23 mm (p = .003) between 30° and 0°. Change in the volume of the IPFP was significantly increased or decreased in eight hyperoctants defined by the tibial coordinate system. The IPFP moved from the postero-supero hyperoctants to anterior hyperoctants. Significant correlations were observed between the IPFP and mobility of the patella, patellar tendon or tibia.ConclusionThe IPFP moves antero-inferiorly during quasi-static knee extension from 30 to 0° in young healthy individuals. Comparisons of IPFP behavior between the healthy and pathological knees may help us understand the role of IPFP and problems caused by IPFP contracture in future studies.     

Middle patellar tendon to posterior cruciate ligament (PT–PCL) and normalized PT–PCL: New magnetic resonance indices for tibial tubercle position in patients with patellar instability

Background

To demonstrate whether the distance between the middle point of the patellar tendon and posterior cruciate ligament (PT–PCL) calculated on a single axial MR image could be an alternative measure to tibial tubercle–PCL (TT–PCL) distance for TT lateralization without the need of imaging processing. To show that normalization of PT–PCL (nPT-PCL) against the maximum diameter of the tibial plateau may help to identify patients with patellar instability (PI).

Comparison between navigated reported position and postoperative computed tomography to evaluate accuracy in a robotic navigation system in total knee arthroplasty

BackgroundComputer navigation increases reproducibility compared to non-navigated total knee arthroplasty (TKA). Robotics navigation is a branch of computer navigation technology that might further improve accuracy of implant placement. The aim of this study is to assess the accuracy achieved in TKA with a robotic navigation system.MethodsOne hundred seventy three knees. System studied: Omni navigation System (OMNI, Raynham, MA). Navigated femoral and tibial cuts were compared to postoperative computed tomography (CT). Measurements reviewed: femoral coronal alignment (FCA), femoral sagittal alignment (FSA), femoral rotational alignment (FRA), tibial coronal alignment (TCA), tibial sagittal alignment (TSA) and hip–knee–ankle (HKA) angle. Statistical analysis was made using R.ResultsThe mean differences between the navigated reported and the CT positions were: FCA: 0.1 ± 1.2° more varus (P = 0.58), FSA: 1.5 ± 0.3° more flexed (P < 0.001), FRA: 0.0 ± 1.7° (P = 0.93), TCA: 0.7 ± 1.1° more varus (P < 0.001), TSA: − 1.3 ± 1.5 more negative slope (P < 0.001), HKA angle: 0.4 ± 2.4 more varus (P < 0.049).The percentages of concordance inside a three degree difference were: FCA: 98% (169 knees), FSA: 100% (173 knees), FRA: 94% (162 knees), TCA: 99% (171 knees), TSA: 93% (161 knees) and HKA angle: 83% (144 knees).ConclusionsThe current study showed that the robotic navigation system studied is highly accurate regarding final implant positioning for FCA, FRA and TCA. It has less accuracy in FSA, TSA and the HKA angle.     

Histopathological changes in the infrapatellar fat pad in an experimental rabbit model of early patellofemoral osteoarthritis

Background

The purpose of this study was to characterise the histopathological changes in the infrapatellar fat pad (IPFP) in the early stage of patellofemoral osteoarthritis (PFOA).

Knee laxity in anterolateral complex injuries versus lateral meniscus posterior horn injuries in anterior cruciate ligament deficient knees: A cadaveric study

BackgroundIn the anterior cruciate ligament (ACL) injured knee, additional injury of the anterolateral ligament (ALL) and capsule may increase the pathologic laxity. The purpose of this study was to compare the effects of the anterolateral complex (ALC) injury in ACL injured knee with the effects of lateral meniscus posterior horn (LMPH) meniscectomy.MethodsTen fresh-frozen cadaveric knees were used. After testing the (1) intact knees and (2) ACL sectioned knees (ACL-), two groups were established: an (3) ALC sectioning group (n = 5), which underwent additional ALC sectioning (ACL-/ALC-) after ACL sectioning, and a separate (3) LMPH meniscectomy group (n = 5) that underwent LMPH meniscectomy (ACL-/LMPH-) after ACL sectioning. Knee laxity was measured in terms of internal-external rotation, anterior–posterior translation, and varus-valgus angulation for each condition at knee flexion angles of 0°, 30°, 60° and 90°.ResultsAfter additional sectioning of the ALC (ACL-/ALC-), the mean internal rotation at 0, 30, 60 and 90° of knee flexion was 11.9 ± 1.3°, 18.1 ± 1.6°, 18.3 ± 1.8°, and 17.8 ± 2.4°, respectively, showing significant internal rotation laxity when compared to the intact knee (P = .031, .020, .001 and .033). Anterior translation also significantly increased compared to the ACL- knee at 30° (12.7 ± 1.4 to 16.8 ± 1.7 mm: P = .039). In contrast, additional meniscectomy of the LMPH (ACL-/LMPH-) significantly increased valgus laxity compared to the intact knee at 30, 60 and 90° (P = .021, .018 and .024).ConclusionThese findings suggest that the anterolateral complex, which include the ALL and anterolateral capsule, may play an important role in stabilizing the knee against internal rotation and anterior translation.     

Hip kinematics during a stop-jump task in patients with chronic ankle instability

Context:

Chronic ankle instability (CAI) commonly develops after lateral ankle sprain. Movement pattern differences at proximal joints may play a role in instability.

Objective:

To determine whether people with mechanical ankle instability (MAI) or functional ankle instability (FAI) exhibited different hip kinematics and kinetics during a stop-jump task compared with “copers.”

Design:

Cross-sectional study.

Setting:

Sports medicine research laboratory.

Patients or Other Participants:

Sixty-three recreational athletes, 21 (11 men, 10 women) per group, matched for sex, age, height, mass, and limb dominance. All participants reported a history of a moderate to severe ankle sprain. The participants with MAI and FAI reported 2 or more episodes of giving way at the ankle in the last year and decreased functional ability; copers did not. The MAI group demonstrated clinically positive anterior drawer and talar tilt tests, whereas the FAI group and copers did not.

Intervention(s):

Participants performed a maximum-speed approach run and a 2-legged stop jump followed by a maximum vertical jump.

Main Outcome Measure(s):

An electromagnetic tracking device synchronized with a force plate collected data during the stance phase of a 2-legged stop jump. Hip motion was measured from initial contact to takeoff into the vertical jump. Group differences in hip kinematics and kinetics were assessed.

Results:

The MAI group demonstrated greater hip flexion at initial contact and at maximum (P = .029 and P = .017, respectively) and greater hip external rotation at maximum (P = .035) than the coper group. The MAI group also demonstrated greater hip flexion displacement than both the FAI (P = .050) and coper groups (P = .006). No differences were noted between the FAI and coper groups in hip kinematic variables or among any of the groups in ground reaction force variables.

Conclusions:

The MAI group demonstrated different hip kinematics than the FAI and coper groups. Proximal joint motion may be affected by ankle joint function and laxity, and clinicians may need to assess proximal joints after repeated ankle sprains.