Anterior cruciate ligament (ACL) injuries are among the most common and debilitating knee injuries in professional athletes with an incidence in females up to eight-times higher than their male counterparts. ACL injuries can be career-threatening and are associated with increased risk of developing knee osteoarthritis in future life. The increased risk of ACL injury in females has been attributed to various anatomical, developmental, neuromuscular, and hormonal factors. Anatomical and hormonal factors have been identified and investigated as significant contributors including osseous anatomy, ligament laxity, and hamstring muscular recruitment. Postural stability and impact absorption are associated with the stabilizing effort and stress on the ACL during sport activity, increasing the risk of noncontact pivot injury. Female patients have smaller diameter hamstring autografts than males, which may predispose to increased risk of re-rupture following ACL reconstruction and to an increased risk of chondral and meniscal injuries. The addition of an extra-articular tenodesis can reduce the risk of failure; therefore, it should routinely be considered in young elite athletes. Prevention programs target key aspects of training including plyometrics, strengthening, balance, endurance and stability, and neuromuscular training, reducing the risk of ACL injuries in female athletes by up to 90%. Sex disparities in access to training facilities may also play an important role in the risk of ACL injuries between males and females. Similarly, football boots, pitches quality, and football size and weight should be considered and tailored around females’ characteristics. Finally, high levels of personal and sport-related stress have been shown to increase the risk of ACL injury which may be related to alterations in attention and coordination, together with increased muscular tension, and compromise the return to sport after ACL injury. Further investigations are still necessary to better understand and address the risk factors involved in ACL injuries in female athletes. Cite this article:
To investigate changes in quadriceps and
Injuries to the
Anterior cruciate ligament reconstruction (ACLR) using a semitendinosus (ST) autograft, with or without gracilis (GR), results in donor muscle atrophy and varied tendon regeneration. The effects of harvesting these muscles on muscle moment arm and torque generating capacity have not been well described. This study aimed to determine between-limb differences (ACLR vs uninjured contralateral) in muscle moment arm and torque generating capacity across a full range of hip and knee motions. A secondary analysis of magnetic resonance imaging was undertaken from 8 individuals with unilateral history of ST-GR ACLR with complete ST tendon regeneration. All
Background. Revision total knee arthroplasties (rTKA) are performed with increasing frequency due to the increasing numbers of primary arthroplasties, but very little is known regarding the influence of muscle strength impairments on functional limitations in this population. Objectives. The aim of this study was to assess relationship between muscle strength and functional level in patient with rTKA. Design and Methods. Twenty-three patients (8 males, 15 females) were included in the study with mean age 68.4±10 years. Patients performed 3 performance tests (50-Step Walking Test, 10 Meter Walk Test, 30-Second Chair-Stand Test), and one self-report test (HSS) were preferred to assess patients. The maximum isometric muscle strength of quadriceps femoris and
The jackaling position within rugby has not been previously described as a mechanism for proximal hamstring injuries. This prospective single surgeon study included 54 professional rugby players (mean age 26 ± 4.8 years) undergoing acute primary surgical repair of complete, proximal hamstring avulsion injuries confirmed on preoperative magnetic resonance imaging. All study patients underwent a standardised postoperative rehabilitation programme. Predefined outcomes were recorded at regular intervals. Mean follow-up time was 17 months (range, 12 months to 24 months) from date of surgery. 51 patients (94.4%) returned to their pre-injury level of sporting activity. Mean time from surgical repair to full sporting activity was 7 months (range, 4 months to 12 months). Zero patients had recurrence of the primary injury. At 1 year after surgery compared to 3 months after surgery, patients had increased mean isometric
Many patients who undergo a total knee arthroplasty (TKA) wish to return to a more active lifestyle. The implant must be able to restore adequate muscle strength and function. However, this may not be a reality for some patients as quadriceps and
Introduction. Regular, repeated stretching increases joint range of movement (RoM), however the physiology underlying this is not well understood. The traditional view is that increased flexibility after stretching is due to an increase in muscle length or stiffness whereas recent research suggests that increased flexibility is due to modification of tolerance to stretching discomfort/pain. If the pain tolerance theory is correct the same degree of micro-damage to muscle fibres should be demonstrable at the end of RoM before and after a period of stretch training. We hypothesise that increased RoM following a 3 weeks hamstrings static stretching exercise programme may partly be due to adaptive changes in the muscle/tendon tissue. Materials and Methods. Knee angle and torque were recorded in healthy male subjects (n=18) during a maximum knee extension to sensation of pain. Muscle soreness (pain, creatine kinase activity, isometric active torque, RoM) was assessed before knee extension, and 24 and 48 hours after maximum stretch. An exercise group (n=10) was given a daily home hamstring stretching programme and reassessed after 3 weeks and compared to a control group (n=8). At reassessment each subject's
We assessed the functional outcome following fracture of the tibial plateau in 63 consecutive patients. Fifty-one patients were treated by internal fixation, five by combined internal and external fixation and seven non-operatively. Measurements of joint movement and muscle function were made using a muscle dynamometer at three, six and 12 months following injury. Thirteen patients (21%) had a residual flexion contracture at one year. Only nine (14%) patients achieved normal quadriceps muscle strength at 12 months, while 19 (30%) achieved normal
Purpose: To document the recovery of knee function following Medial Collateral Ligament (MCL) injury of the knee. Methods and Results A cohort of 38 consecutive patients with MCL injuries were followed prospectively from the time of injury for a period of one year. There were 13 grade I MCL sprains and 25 grade II sprains. Twelve patients had a concomitant ACL tear. Patients were treated in a hinged knee brace with full extension and 90 degrees of knee flexion for 6 weeks from the date of injury. All patients had an identical rehabilitation programme. Clinical outcome was assessed using two standard functional knee scores (International Knee Documentation Committee (IKDC) score and Knee Outcome Orthopaedic Score (KOOS)). Quadriceps and
Introduction. Unicompartmental knee arthroplasty (UKA) currently experiences increased popularity. It is usually assumed that UKA shows kinematic features closer to the natural knee than total knee arthroplasty (TKA). Especially in younger patients more natural knee function and faster recovery have helped to increase the popularity of UKA. Another leading reason for the popularity of UKA is the ability to preserve the remaining healthy tissues in the knee, which is not always possible in TKA. Many biomechanical questions remain, however, with respect to this type of replacement. 25% of knees with medial compartment osteoarthritis also have a deficient anterior cruciate ligament [1]. In current clinical practice, medial UKA would be contraindicated in these patients. Our hypothesis is that kinematics after UKA in combination with ACL reconstruction should allow to restore joint function close to the native knee joint. This is clinically relevant, because functional benefits for medial UKA should especially be attractive to the young and active patient. Materials and Methods. Six fresh frozen full leg cadaver specimens were prepared to be mounted in a kinematic rig (Figure 1) with six degrees of freedom for the knee joint. Three motion patterns were applied: passive flexion-extension, open chain extension, and squatting. These motion patterns were performed in four situations for each specimen: with the native knee; after implantation of a medial UKA (Figure 2); next after cutting the ACL and finally after reconstruction of the ACL. During the loaded motions, quadriceps and
Introduction: Reconstruction of ruptured anterior cruciate ligament is a commonly performed orthopaedic procedure. There are many ways of reconstructing this ligament. One method of doing so is to harvest a tendon graft from the
Background. In vivo fluoroscopic studies have proven that femoral head sliding and separation from within the acetabular cup during gait frequently occur for subjects implanted with a total hip arthroplasty. It is hypothesized that these atypical kinematic patterns are due to component malalignments that yield uncharacteristically higher forces on the hip joint that are not present in the native hip. This in vivo joint instability can lead to edge loading, increased stresses, and premature wear on the acetabular component. Objective. The objective of this study was to use forward solution mathematical modeling to theoretically analyze the causes and effects of hip joint instability and edge loading during both swing and stance phase of gait. Methods. The model used for this study simulates the quadriceps
Introduction. This study explores whether subjects with bicruciate retaining TKRs (BiCR) have more normal knee biomechanics during level walking and stair ascent than subjects with posterior cruciate retaining TKRs (PCR). Due to anterior cruciate ligament (ACL) preservation, we expect BiCR subjects will not show the reduced flexion and altered muscle activation patterns characteristic of persons with TKRs. Methods. Motion and electromyography (EMG) data were collected during level walking and stair climbing for 16 BiCR subjects (4/12 m/f, 65±3 years, 30.7±7.0 BMI, 8/8 R/L), 17 PCR subjects (2/15 m/f, 65±7 years, 30.4±5.1 BMI, 7/10 R/L), and 17 elderly healthy control subjects (8/9 m/f, 55±10 years, 25.8±4.0 BMI, 10/7 R/L), using the point cluster marker set. Surface EMG electrodes were placed on the vastus medialis obliquus (VMO), rectus femoris (RF), biceps femoris (BF), and semitendinosus (ST) muscles. EMG data are reported as percent relative voluntary contraction (%RVC), normalized to the average peak EMG signals during level walking. Statistical nonparametric mapping was used for waveform analysis. Results. Both TKR groups were older, and PCR subjects had higher BMI than control subjects (p≤0.020). The BiCR group walked slower and with shorter stride lengths than controls (p≤0.012). During level walking, BiCR subjects had less knee extension and posterior tibial displacement than controls (95–98%, 96–100% gait cycle, p=0.003, 0.001). PCR subjects showed higher flexion mid-stance than controls (36–44% gait cycle, p=0.001) and more external rotation (66–69% gait cycle, p=0.003). Both TKR groups had smaller extension moment peaks (PCR 5, 59–75, 96%, BiCR 61–78, 95–97% stance, p≤0.007, 0.003) than the control group. The BiCR group had smaller adduction and external rotation moment peaks (20–24%, 10–18% stance, p=0.003, 0.001) compared with controls. During stair climbing, BiCR subjects displayed more external tibial rotation (4–16% stance), more knee abduction (36–52% stance), and a lower adduction moment peak (24–34% stance) compared to healthy controls (p≤0.005). TKR subjects from both groups showed lower flexion moment peaks than controls (PCR 24–35%, BiCR 24–28% stance, p≤0.001, 0.004). For EMG, PCR subjects had more BF activity during stair ascent versus level walking than healthy subjects (56–74% stance, p≤0.001). Discussion. BiCR and PCR showed more similarities than expected. Both had altered kinematics and kinetics compared to controls, suggesting some intrinsic extensor mechanism weakness, possibly an aftereffect of osteoarthritis. The EMG results agreed accordingly, as both TKR groups showed (non-significant) decreased quadriceps activity during stair climbing. Interestingly, PCR subjects also had more BF activity during stair than healthy controls, a trend that is common for both TKR subjects and people with ACL deficiency. On the other hand, although BiCR subjects were significantly more externally rotated in early stance phase for stair climbing, their rotation patterns began to align more closely to those of the healthy control subjects at lower flexion angles where the ACL should come into play. In conclusion, ACL retention in TKRs does not correct the extensor mechanism deficits commonly found in TKR patients, although it has some effect on secondary knee kinematics and
Background. Currently, hip implant designs are evaluated experimentally using mechanical simulators or cadavers, and total hip arthroplasty (THA) postoperative outcomes are evaluated clinically using long-term follow-up. However, these evaluation techniques can be both costly and time-consuming. Fortunately, forward solution mathematical models can function as theoretical joint simulators, providing instant feedback to designers and surgeons alike. Recently, a validated forward solution model of the hip has been developed that can theoretically simulate new implant designs and surgical technique modifications under in vivo conditions. Objective. The objective of this study was to expand the use of this hip model to function as an intraoperative virtual implant tool, thereby allowing surgeons to predict, compare, and optimize postoperative THA outcomes based on component placement, sizing choices, reaming and cutting locations, and surgical methods. Methods. The math model simulates the quadriceps
Background. While not common in the native hip, occurrences of femoral head separation from the acetabular cup during gait are well documented after total hip arthroplasty. Although the effects of this phenomenon are not well understood, we hypothesize that these atypical kinematics are due to component misalignments that yield uncharacteristic forces on the hip joint that are not present in the native hip. Objective. The objective of this study was to theoretically predict the causes of hip separation during stance phase using forward solution mathematical modelling. Methods. The model simulates the quadriceps
The purpose of this study was to compare lower limb muscle activity in patients who underwent a total knee arthroplasty (TKA) with a medial pivot (MP) implant to healthy controls (CTRL) during a stair ascent task. Seven MP (age: 61.4±6.5 years, BMI: 30.0±4.7 kg/m2, 12.4±3.8 months post-surgery) patients who underwent a TKA performed using either a subvastus or medial parapatellar approach were age- and BMI-matched to seven healthy CTRL participants (age: 62.4±4.2 years, BMI: 26.3±2.7 kg/m2) for comparison in this study. Participants underwent electromyography (EMG) analysis while completing a three-step stairs ascent task. Portable wireless surface EMG probes were placed on the vastus lateralis (VL), rectus femoris (RF), vastus medialis (VM), biceps femoris (BF) and semimembranous (SM) muscles of both lower limbs. Peak linear envelope (peakLE) and total muscle activity (iEMG) were extrapolated and normalised to a maximal voluntary contraction. Nonparametric Kruskal Wallace ANOVA tests were used and Wilcoxon rank sum tests were used to identify where significant (p < 0.05) differences occurred. The operated limb had significantly lower iEMG in the VAL, RF and BF muscles, and significantly lower peakLE in the SM muscle compared to the non-operated limb. The operated-limb of the MP group had significantly lower iEMG in the VAL and BF muscles, and significantly lower peakLE in the VAL, RF and SM muscles compared to the CTRL group. The non-operated limb in the MP group had significantly larger peakLE and iEMG in the RF muscle compared to the CTRL group. Differences in muscle activity between the operated and non-operated limbs in TKA patients with a MP implant demonstrates a compensatory strategy to reduce loading on the operated limb by relying on the non-operated limb. This same strategy has been reported in other studies investigating other functional tasks. This reliance on the non-operated limb resulted by having greater peakLE and iEMG in the RF muscle compared to the healthy CTRLs. These differences between limbs could also result from many years of muscle adaptation waiting to receive a knee replacement. In conclusion, TKA patients exhibit discrepancies in muscle activity compared to healthy knees and differences between operated and non-operated limbs. Post-surgery rehabilitation should rely on unilateral strength exercises of the quadriceps and
1. A method of correcting poliomyelitic lateral rotation deformity of the thigh by transplant of one or more of the
Dual mobility (DM) bearing implants reduce the incidence of dislocation following total hip arthroplasty (THA) and as such they are used for the treatment of hip instability in both primary and revision cases. The aim of this study was to compare lower limb muscle activity of patients who underwent a total hip arthroplasty (THA) with a dual mobility (DM) or a common cup (CC) bearing compared to healthy controls (CON) during a sit to stand task. A total of 21 patients (12 DM, 9 CC) and 12 CON were recruited from the local Hospital. The patients who volunteered for the study were randomly assigned to either a DM or a CC cementless THA after receiving informed consent. All surgeries were performed by the same surgeon using the direct anterior approach. Participants underwent electromyography (EMG) and motion analysis while completing a sit-to-stand task. Portable wireless surface EMG probes were placed on the vastus lateralis, rectus femoris, biceps femoris, semitendinosus (ST), gluteus medius and tensor fasciae latae muscles of the affected limb in the surgical groups and the dominant limb in the CON group. Motion capture was used to record lower limb kinematics and kinetics. Muscle strength was recorded using a hand-held dynamometer during maximal voluntary isometric contraction (MVIC) testing. Peak linear envelope (peakLE) and total muscle activity (iEMG) were extrapolated and normalized to the MVIC and time cycle for the sit to stand task. Using iEMG, quadriceps-hamstrings muscle co-activation index was calculated for the task. Nonparametric Kruskal Wallace ANOVA tests and Wilcoxon rank sum tests were used to identify where significant (p < 0.05) differences occurred. The DM group had greater iEMG of the ST muscle compared to the CC (p=0.045) and the CON (p=0.015) groups. The CC group had lower iEMG for
Introduction. Total knee arthroplasty (TKA) is a well proven surgical procedure. Squat and gait motions are common activities in daily life. However, squat motion is known as most dissatisfying motion in activities in daily life after total knee arthroplasty (TKA). Dissatisfaction after TKA might refer to muscle co-contraction between quadriceps and hamstrings. The purposed of this study was to develop squat and gait simulation model and analyses the contact mechanics and quadriceps and