Does the Q angle reflect the force on the patella in the frontal plane?

The Effect of Q Angle and Hamstring Length on Balance Performance in Gonarthrosis Patients

Introduction Gonarthrosis (G) is a progressive disease that affects the knee joint and causes pain and limitation of movement in the knee. The determination of the morphometric status of G patients has been a subject of interest recently. The purpose of this study is to determine how hamstring length (HL) and patellofemoral angle (Q angle [QA]) affect the ability of individuals with G to maintain balance. Methods A total of 80 (40 G patients and 40 in the control group [CG]) participants aged 40-65 were included in the study. A goniometer was used to measure the participants' QA. The mean age of the participants was 50.18±7.16 in the G group and 51.40±6.64 in CG. HL was measured using the sit-and-reach test. Participants' dynamic balance state was evaluated using the Y balance test by stepping in the following directions: right-anterior (R-An), right-posteromedial (R-Pm), right-posterolateral (R-Pl), left-anterior (L-An), left-posteromedial (L-Pm), and left-posterolateral (L-Pl). Results According to the results of this research, the balance performance of G patients was significantly lower in all directions (R-An, R-Pm, R-Pl, L-An, L-Pm, L-Pl) compared to the CG. In both groups, R-QA, L-QA, and HL did not change. However, linear regression analysis indicated that in G patients, R-QA, L-QA, and HL affected balance performance. No significant interaction was found between these parameters and balance performance in the CG. Conclusion HL and QA have a significant role in determining body balance. In our study, we found that QA decreased in G patients, leading to genu varum in these individuals. The hamstring muscle shortening observed in G patients significantly negatively affected balance, especially in the R-An, R-Pm, L-An, L-Pm, and L-Pl directions. For healthcare professionals preparing treatment protocols for G patients, we recommend providing exercises to improve balance, especially in these directions.

Extensor mechanism tendinopathy in patients with lateral patellar maltracking

OBJECTIVE

Patellar maltracking is an important subset of patellofemoral pain syndrome. We hypothesize that maltracking patients have an increased incidence of extensor mechanism dysfunction due to repetitive attempts at stabilization of the patella. Our purpose is to delineate imaging features to identify maltracking patients at risk for extensor mechanism tendinopathy.

MATERIALS AND METHODS

Retrospective review of knee MRIs performed for anterior knee pain over a year was conducted to identify 218 studies with imaging findings of maltracking. The cases were evaluated for the presence and degree of patellar and quadriceps tendinopathy, tibial tuberosity-trochlear groove distance (TT-TG) and the distribution and grade of patellofemoral chondrosis. Cases were compared to 100 healthy, age-matched control knee MRIs.

RESULTS

The mean age of maltracking patients with either patellar or quadriceps tendinosis was 41.2 years versus 48.2 years in the control population (p = 0.037). The TT-TG was significantly higher in maltracking patients with either patellar or quadriceps tendinosis at 16.49 mm versus 14.99 mm (p = 0.006). Maltrackers with isolated lateral patellofemoral chondrosis had a higher mean TT-TG at 17.4 mm versus 15.4 mm (p = 0.007). Extensor mechanism tendinosis was increased in the maltracking population compared to the controls at 57.8% versus 27.3% (p = 0.004).

CONCLUSION

Extensor mechanism tendinosis is more common in the maltracking population and occurs at a younger age. TT-TG distance is significantly increased in patients with extensor mechanism dysfunction and in patients with isolated lateral patellofemoral chondrosis. TT-TG measurement can be used independently to identifying maltrackers who may be at risk for future complications.

Assessment of quadriceps angle in children aged between 2 and 8 years

Aim:

The quadriceps angle is the angle between the line drawn from the spina iliaca anterior superior to the midpoint of the patella, and the line drawn from the midpoint of the patella to the tuberositas tibiae. It is important for lower extremity posture. The aim of this study was to determine the normative quadriceps angle value by measurement, and to assess the probable effect of factors such as measurement position, age, sex, and presence of pes planus on these values.

Material and Methods:

A total of 599 children consisting of 296 (49.4%) girls and 303 (50.6%) boys aged between 2 and 8 years, were included in the study. The children were divided into three groups by age as 2–4 years, 4–6 years, and 6–8-years. After the children’s demographic data were collected, the quadriceps angle was measured using an electronic goniometer. Pes planus was assessed by drawing the Feiss line.

Results:

In bilateral measurement, it was found that the quadriceps angle decreased with age both in the supine and standing positions (p<0.05). It was observed that sex and presence of pes planus had no effect on the quadriceps angle independent from measurement positions (p>0.05). A low negative correlation was found between body mass index and the quadriceps angle in both measurement positions (p<0.05).

Conclusion:

It was found that positional changes and weight bearing on limbs did not cause any change in knee position in healthy children. We consider that the decrease in quadriceps angle in this age group is due to growth rate asymmetry between the femur shaft and pelvic diameter.

Association of tibiofemoral angle, quadriceps angle and body mass index in a selected adolescent population

Background:

Tibiofemoral angle (TFA) and quadriceps angle (QA) are important in the evaluation of patients with knee pathologies associated with these angles.

Objectives:

This study investigated correlations among TFA, QA and body mass index (BMI) among Nigerian adolescent population.

Methods:

A total of 519 (262 males and 257 females) adolescents aged between 10–18 years selected by stratified random sampling technique from some randomly selected schools in Nnewi metropolis. This study utilised the cross-sectional survey design. A height meter and bathroom weighing scale were used to collect data for BMI while a universal plastic goniometer was used to measure TFA and QA. Independent t- test, paired t-test and Pearson Product Moment Correlation were used to analyse the data obtained.

Results:

Findings of this study showed there was significant difference between right and left QA of males (t= 2.824; p= 0.005), and females (t= −2.012; p= 0.045) with the right QA been higher than the left in both males and females. Males have a higher TFA and QA (p<0.05 in all cases) than females. A significant negative correlation was found between BMI and right TFA (p=0.034), and between TFA and QA (p= <0.0001).

Conclusion:

TFA positively significantly correlated with QA, with males having higher QA and TFA than females. The obtained information is important in the assessment and management of knee pathologies associated with these angles.

Influence of quadriceps angle on static and dynamic balance in young adults

BACKGROUND

Changes in postural stability may be a reason for injuries in individuals who have altered musculoskeletal alignment. Q angle (QA) has shown to be a predictor for lower extremity injuries. However, the relationship between balance and QA has not been investigated in young adults.

OBJECTIVE

The aim of the study was to investigate the relationship between QA and balance in young adults.

METHODS

Ninety participants performed the single leg stance test (SLST) and Star Excursion Balance Test (SEBT) to assess static and dynamic balance, respectively. QA was measured using a manual goniometer. Participants were divided into low, normal and high QA groups.

RESULTS

The relationship between SLST and QA was not statistically significant in both eyes opened and closed condition (r=-0.030, p= 0.782; r= 0.031, p= 0.774; respectively). SLST scores did not differ among the three groups in both eyes opened and closed condition (p= 0.781, p= 0.790; respectively). QA significantly correlated with lateral, posterolateral directions and sum score of SEBT (r= 0.240, p= 0.023; r= 0.269, p= 0.010; r= 0.210, p= 0.047). The comparisons among the low, normal and high Q angle groups' SEBT scores showed that balance performance in lateral direction was poorer in low QA group (p= 0.027).

CONCLUSIONS

The results of the study showed that QA and dynamic balance have a significant relationship. To reduce musculoskeletal injury risk, the dynamic balance should be assessed in young adults who have lower QA.

Dynamic knee valgus kinematics and their relationship to pain in women with patellofemoral pain compared to women with chronic hip joint pain

BACKGROUND

Dynamic knee valgus (DKV) is an abnormal movement pattern visually characterized by excessive medial movement of the lower extremity during weight bearing. Differences in hip and knee kinematic components of DKV may explain the emergence of different pain problems in people who exhibit the same observed movement impairment. Using a secondary analysis of exiting data sets, we sought to determine whether hip and knee frontal and transverse plane angles during a functional task differed between women with patellofemoral pain and women with chronic hip joint pain, and the relationship between joint-specific kinematics and pain in these 2 pain populations.

METHODS

In the original studies, 3-dimensional hip and knee kinematics during a single leg squat were obtained in 20 women with patellofemoral pain and 14 women with chronic hip joint pain who demonstrated visually classified DKV. Pain intensity during the squat was assessed in both groups. For the secondary analysis, kinematic data were compared between pain groups using their respective control groups as a reference. Within each pain group, correlation coefficients were used to determine the relationship between kinematics and pain during the squat.

RESULTS

Hip adduction and contralateral pelvic drop were greater in those with chronic hip joint pain compared to those with patellofemoral pain (effect sizes ≥ 0.40). Greater knee external rotation (r=0.47, p=0.04) was correlated with greater knee pain in those with patellofemoral pain, while greater hip adduction (r =0.53, p =0.05) and greater hip internal rotation (r =0.55, p =0.04) were correlated with greater hip pain in those with chronic hip joint pain.

CONCLUSION

Hip frontal plane motion was greater in those with chronic hip joint pain compared to those with patellofemoral pain. In both groups, greater abnormal movement at the respective joint (e.g. knee external rotation in the patellofemoral pain group and hip adduction and internal rotation in the chronic hip joint pain group) was associated with greater pain at that joint during a single leg squat.

Relationship between knee abduction moment with patellofemoral joint reaction force, stress and self-reported pain during stair descent in women with patellofemoral pain

BACKGROUND

Increased external knee abduction moment has been proposed as a risk factor for patellofemoral pain. This alteration is thought to be associated with elevated patellofemoral joint reaction force and stress, however these relationships remain poorly explored. Therefore, this study aimed at comparing knee abduction moment parameters (peak, rate of moment development and impulse), patellofemoral joint reaction force and stress of women with patellofemoral pain and pain-free controls during stair descent; and investigating the relationship among these variables with self-reported pain.

METHODS

Kinetic data was obtained by inverse-dynamics equations and a previously reported algorithmic model was used to determine patellofemoral joint reaction force and stress. Participants' worst pain in the last month and pain level during stair descent were evaluated using a visual analogue scale.

FINDINGS

Women with patellofemoral pain presented higher peak, rate of moment development and impulse of the external knee abduction moment, patellofemoral joint reaction force and stress (p = 0.005 to 0.04, effect size = 0.52 to 0.96) during stair descent than pain-free controls. Only knee abduction moment impulse presented positive moderate correlations with worst pain level in the last month (r = 0.53, p < 000.1), pain level during stair descent (r = 0.33, p = 0.042), patellofemoral joint reaction force (r = 0.65, p < 000.1) and stress (r = 0.58, p < 000.1).

INTERPRETATION

These findings indicate that strategies aimed at decreasing external knee abduction moment impulse could reduce the load over the patellofemoral joint and improve pain of women with patellofemoral pain.

Association between measures of patella height, morphologic features of the trochlea, and patellofemoral joint alignment: the MOST study

BACKGROUND

Patellofemoral joint (PFJ) malalignment (lateral patella displacement and tilt) has been proposed as a cause of patellofemoral pain. Patella height and/or the morphologic features of the femoral trochlea may predispose one to patella malalignment.

QUESTIONS/PURPOSES

The purposes of our study were to assess the associations among patella height, morphologic features of the trochlea, and measures of PFJ alignment and to determine which measures of patella height and morphologic features of the trochlea were the best predictors of PFJ alignment.

METHODS

Measures of patella height (Insall-Salvati ratio and modified Insall-Salvati ratio), morphologic features of the trochlea (sulcus angle, trochlear angle, lateral trochlear inclination, medial trochlear inclination), and PFJ alignment (bisect offset and patella tilt angle) were assessed in 566 knees from the Multicenter Osteoarthritis Study.

RESULTS

Bisect offset was correlated with the Insall-Salvati ratio (r = 0.25) and lateral trochlear inclination (r = -0.38). Patella tilt angle correlated with the trochlear angle (-0.27) and lateral trochlear inclination (-0.32). Linear regression models including the Insall-Salvati ratio and lateral trochlear inclination explained 20% and 11% of the variance in bisect offset and patella tilt angle, respectively.

CONCLUSIONS

Of the variables measured in the current study, the Insall-Salvati ratio and lateral trochlear inclination were the best predictors of lateral patella displacement and lateral tilt. This knowledge will aid clinicians in the identification of anatomic risk factors for PFJ malalignment and/or PFJ dysfunction.

The vector of quadriceps pull is directed from the patella to the femoral neck

BACKGROUND

The quadriceps is the primary extensor of the knee. Its vector, which is perpendicular to the flexion axis of the knee, is important in understanding knee function and properly aligning total knee components. Three-dimensional (3-D) imaging enables evaluation using a 3-D model of each quadriceps component.

QUESTIONS/PURPOSES

We calculated the direction and magnitude of the quadriceps vector (QV) and the precision of the measurement, and asked whether the QV bears a constant relationship to the femur and is aligned with an anatomically based axis on the femur.

METHODS

Using CT data of 14 subjects, we created a 3-D solid model of each quadriceps muscle component. Vectors (3-D direction and length) for each quadriceps component were determined using principal component analysis for muscle direction and volume for magnitude; vector addition established the directional vector of the combined muscle. The combined vector originating in the center of the patella was compared with the shaft, mechanical, and spherical (center femoral head to center medial side of the knee) axes.

RESULTS

The QV passed from the patella center proximally crossing the femoral neck between the femoral head and greater trochanter and was most closely aligned with the spherical axis.

CONCLUSIONS

The QV axis may be an important reference for alignment of total knee components.

CLINICAL RELEVANCE

The spherical axis can be used in aligning total knee components to the flexion axis of the knee.

The influence of abnormal hip mechanics on knee injury: a biomechanical perspective

During the last decade, there has been a growing body of literature suggesting that proximal factors may play a contributory role with respect to knee injuries. A review of the biomechanical and clinical studies in this area indicated that impaired muscular control of the hip, pelvis, and trunk can affect tibiofemoral and patellofemoral joint kinematics and kinetics in multiple planes. In particular, there is evidence that motion impairments at the hip may underlie injuries such as anterior cruciate ligament tears, iliotibial band syndrome, and patellofemoral joint pain. In addition, the literature suggests that females may be more disposed to proximal influences than males. Based on the evidence presented as part of this clinical commentary, it can be argued that interventions which address proximal impairments may be beneficial for patients who present with various knee conditions. More specifically, a biomechanical argument can be made for the incorporation of pelvis and trunk stability, as well as dynamic hip joint control, into the design of knee rehabilitation programs.

LEVEL OF EVIDENCE

Aetiology/therapy, level 5.

Influence of knee alignment on quadriceps cross-sectional area

Previous studies of methods for stimulating the individual muscles composing the quadriceps femoris have not considered the structural features of a subject's knee joint. In this study, we compared the ratios of the individual muscles composing the quadriceps between subjects with different knee alignments using magnetic resonance (MR) imaging. A total of 18 healthy males were examined: 6 normal knees (age, 23.0+/-0.6 yr; femorotibial angle (FTA), 176.8+/-0.4 degrees), 6 genu varum (age, 21.8+/-2.9 yr; FTA, 181.7+/-2.6 degrees) and 6 genu valgum (age, 21.0+/-1.6 yr; FTA, 172.3+/-1.5 degrees). The cross-sectional areas (CSAs) of quadriceps muscles were obtained by MR imaging of the entire left thigh. The CSAs of the vastus lateralis (VL), rectus femoris (RF), vastus medialis (VM) and vastus intermedius (VI) muscles were obtained by MR imaging of the entire left thigh in a supine position. The VM/VL ratio was also obtained by dividing the CSA of the VM by that of the VL and compared among the three groups of subjects with different knee alignments. The genu varum group showed a significantly higher %CSA of VM in the CSA of the quadriceps (VM/Quad) (49.0+/-2.6%) than values for the other two groups. The genu valgum group showed significantly higher values of RF/Quad (15.2+/-2.1%) and VL/Quad (40.6+/-4.0%) than the other groups. The VM/VL ratio was significantly higher in the genu varum than in values for the other two groups. This difference in CSA, in respect to knee alignment, may be considered when devising muscle training programs.

Relationships between lower extremity alignment and the quadriceps angle

OBJECTIVE

To determine the extent to which select lower extremity alignment characteristics of the pelvis, hip, knee, and foot are related to the Q angle.

DESIGN

Descriptive cohort study design.

SETTING

Applied Neuromechanics Research Laboratory.

PARTICIPANTS

Two hundred eighteen participants (102 males, 116 females).

ASSESSMENT OF RISK FACTORS

Eight clinical measures of static alignment of the left lower extremity were measured by a single examiner to determine the impact of lower extremity alignment on the magnitude of Q angle.

MAIN OUTCOME MEASURES

Q angle, pelvic angle, hip anteversion, tibiofemoral angle, genu recurvatum, tibial torsion, navicular drop, and femur and tibia length.

RESULTS

Once all alignment variables were accounted for, greater tibiofemoral angle and femoral anteversion were significant predictors of greater Q angle in both males and females. Pelvic angle, genu recurvatum, tibial torsion, navicular drop, and femur to tibia length ratio were not significant independent predictors of Q angle in males or females.

CONCLUSIONS

Greater femoral anteversion and tibiofemoral angle result in greater Q angle, with changes in tibiofemoral angle having a substantially greater impact on the magnitude of the Q angle compared with femoral anteversion. As such, the Q angle seems to largely represent a frontal plane alignment measure. As many knee injuries seem to result from a combination of both frontal and transverse plane motions and forces, this may in part explain why Q angle has been found to be a poor independent predictor of lower extremity injury risk.

The reliability and validity of the Q-angle: a systematic review

The quadriceps or Q-angle is an index of the vector for the combined pull of the extensor mechanisms and the patellar tendon. It is used as an indicator for patellofemoral joint dysfunction. The purpose of this article is to systematically review and appraise the literature to determine the reliability and validity of this test. An electronic database search was performed accessing AMED, British Nursing Index, CINAHL, the Cochrane database, EMBASE, ovid Medline, Physiotherapy Evidence Database (PEDro), PsycINFO, Pubmed and Zetoc to April 2008. All English language, human subject, clinical trials, assessing the inter- or intra-tester reliability, or the criterion validity, were included. The Critical Appraisal Skills Programme appraisal tool was used to establish the methodological quality of each study. Ten articles including 569 control and 179 patellofemoral disorder knees were reviewed. The findings suggest that there is considerable disagreement on the reliability and validity of the clinical Q-angle measurement. This may be due to a lack of standardisation in the measurement procedure. Further study is advocated to re-evaluate this topic using well-designed, and sufficiently large observational studies of specific patellofemoral dysfunction populations.

Differences in lower extremity anatomical and postural characteristics in males and females between maturation groups

STUDY DESIGN

Descriptive, cross-sectional.

OBJECTIVES

We compared lower extremity anatomical characteristics in males and females between different maturation groups.

BACKGROUND

Sex differences have been observed in lower extremity anatomical characteristics. While the reasons contributing to these sex differences in adults are unknown, there is evidence that anatomy and posture change considerably during growth and development.

METHODS AND MEASURES

One hundred seventy-three young athletes (age range, 9-18 years) were assessed for stage of maturation and placed into 1 of 3 groups, according to Tanners stages 1 and 2 (MatGrp1), 3 and 4 (MatGrp2), and 5 (MatGrp3). Participants were measured for pelvic angle, hip anteversion, quadriceps angle, tibiofemoral angle, femur length, tibial length, genu recurvatum, tibial torsion, navicular drop, general joint laxity, and anterior knee laxity. Data were compared by sex and maturation group.

RESULTS

When comparing maturation groups, limb length, pelvic angle, and tibial torsion increased with maturation, and anterior knee laxity, genu recurvatum, tibiofemoral angle, and foot pronation decreased with maturation. Females had greater general joint laxity, hip anteversion, and tibiofemoral angles, and shorter femur and tibial lengths than males, regardless of maturation group. Maturational changes in knee laxity and quadriceps angles were sex dependent.

CONCLUSIONS

We observed a general change of posture with maturation that began with greater knee valgus, knee recurvatum, and foot pronation in MatGrp1, then moved toward a relative straightening and external rotation of the knee, and supination of the foot in later maturation groups. While the majority of the measures changed similarly in males and females across maturation groups, decreases in quadriceps angles and anterior knee laxity were greater in males compared to females, and females were observed to have a more inwardly rotated hip and valgus knee posture, compared to males, particularly in later maturation groups.

Hip strength and hip and knee kinematics during stair descent in females with and without patellofemoral pain syndrome

STUDY DESIGN

Cross-sectional.

OBJECTIVE

To determine if females presenting with patellofemoral pain syndrome (PFPS) from no discernable cause other than overuse demonstrate hip weakness and increased hip internal rotation, hip adduction, and knee valgus during stair descent.

BACKGROUND

Historically, PFPS has been viewed exclusively as a knee problem. Recent findings have indicated an association between hip weakness and PFPS. Researchers have hypothesized that patients who demonstrate hip weakness would exhibit increased hip internal rotation, hip adduction, and knee valgus during functional activities. To date, researchers have not simultaneously examined hip and knee strength and kinematics in subjects with PFPS to make this determination.

METHODS AND MEASURES

Eighteen females diagnosed with PFPS and 18 matched controls participated. Strength measures were taken for the hip external rotators and hip abductors. Hip and knee kinematics were collected as subjects completed a standardized stair-stepping task. Independent t tests were used to determine between-group differences in strength and kinematics during stair descent.

RESULTS

Subjects with PFPS generated 24% less hip external rotator (P = .002) and 26% less hip abductor (P =. 006) torque. No between-group differences (P > .05) were found for average hip and knee transverse and frontal plane angles during stair descent.

CONCLUSION

Subjects with PFPS had significant hip weakness but did not demonstrate altered hip and knee kinematics as previously theorized. Additional investigations are needed to better understand the association between hip weakness and PFPS etiology.

Quadriceps angle and risk of injury among high school cross-country runners

DESIGN

Prospective cohort study.

OBJECTIVES

To determine the relationship between quadriceps angle (Q-angle) and risk of lower extremity injury among adolescent cross-country runners.

BACKGROUND

No consensus exists on the role of the Q-angle as a risk factor for lower-extremity overuse injury, especially the effect of large Q-angle or right-left Q-angle difference.

METHODS AND MEASURES

The Q-angles of 393 high school cross-country runners, 13 to 19 years of age, were goniometrically measured in a static, standing position with quadriceps relaxed. The runners were followed during a cross-country season to assess lower extremity injuries resulting from running in practices or competitions.

RESULTS

Runners with a Q-angle >20 degrees were at 1.7 times greater risk of injury (relative risk [RR], 1.7; 95% confidence interval [CI]: 1.2, 2.4) compared with runners whose Q-angle was 10 degrees to <15 degrees . The RR estimates were similar among girls and boys. Runners with >4 degrees absolute right-left Q-angle difference were at 1.8 times greater risk (RR, 1.8; 95% CI: 1.4, 2.5) compared to runners with a smaller difference. Runners with a Q-angle >20 degrees were more likely to injure their knee, while runners with >4 degrees Q-angle difference were more likely to injure their shin. Runners with a Q-angle >20 degrees had greater time lost due to injury.

CONCLUSIONS

High school cross-country runners with large or asymmetric Q-angles may be at greater risk for running injury. Our study suggests that Q-angle measurement be included in preseason screening exams.

Are differences in leg length predictive of lateral patello-femoral pain?

BACKGROUND AND PURPOSE

Lateral patello-femoral pain can shorten an athletic career and generally decrease an individual's physical activity and functional level, such as preventing stair climbing and reducing the ability to rise from a chair. Leg length inequality is associated with patello-femoral pain. A leg length test that best distinguishes the difference between people who have lateral patello-femoral pain and those who do not would have clinical utility. The purpose of the present study was, first, to determine if unilateral, lateral patello-femoral pain was associated with the longer leg when inequality of leg lengths existed and, second, to determine if leg length direct measurement, indirect measurement or quadriceps angle (Q angle) could correctly classify participants according to the presence or absence of patello-femoral pain.

METHOD

The study used an ex post facto, two-group quasi-experimental design. A volunteer sample of 52 participants (14 males, 38 females), ranged in age from 18 to 52 years. Three methods were used to measure leg lengths: palpation meter (PALM) on anterior superior iliac spines (ASIS) while participants maintained centred weight-bearing position on a high resolution pressure mat; tape measurement from ASIS to medial malleolus (supine); tape measurement from ASIS to lateral malleolus (supine). Additionally, Q angle was measured in supine position. Patellar grind test, medial retinacular and lateral patellar palpation screened for patello-femoral pain.

RESULTS

Logistic regression analysis determined correctness of membership in painful and non-painful patello-femoral groups. The PALM method of indirect measurement of leg length differences overall correctly classified approximately 83 % of the participants. Tape measure to medial and lateral malleoli as well as Q angle did not yield significant results.

CONCLUSION

The results suggested that the PALM method of measuring leg length differences may have clinical utility in differentiating between patients who are likely to sustain patello-femoral pain syndrome and those who will not.

Physical Examination and Patellofemoral Pain Syndrome

Patellofemoral pain syndrome, which accounts for 25% of all sports-related knee injuries, is multifactorial in origin. A combination of variables, including abnormal lower limb biomechanics, soft-tissue tightness, muscle weakness, and excessive exercise, may result in increased cartilage and subchondral bone stress, patellofemoral pain, and subtle or more overt patellar maltracking. Because of the multiple forces affecting the patellofemoral joint, the clinical evaluation and treatment of this disorder is challenging. An extensive search of the literature revealed no single gold-standard test maneuver for that disorder, and the reliability of the maneuvers described was generally low or untested. An abnormal Q-angle, generalized ligamentous laxity, hypomobile or hypermobile tenderness of the lateral patellar retinaculum, patellar tilt or mediolateral displacement, decreased flexibility of the iliotibial band and quadriceps, and quadriceps, hip abductor, and external rotator weakness were most often correlated with patellofemoral pain syndrome.

The influence of altered lower-extremity kinematics on patellofemoral joint dysfunction: a theoretical perspective

Although patellofemoral pain (PFP) is recognized as being one of the most common disorders of the lower extremity, treatment guidelines and underlying rationales remain vague and controversial. The premise behind most treatment approaches is that PFP is the result of abnormal patellar tracking and/or patellar malalignment. Given as such, interventions typically focus on the joint itself and have traditionally included strengthening the vastus medialis oblique, taping, bracing, soft tissue mobilization, and patellar mobilization. More recently, it has been recognized that the patellofemoral joint and, therefore, PFP may be influenced by the interaction of the segments and joints of the lower extremity. In particular, abnormal motion of the tibia and femur in the transverse and frontal planes may have an effect on patellofemoral joint mechanics. With this in mind, interventions aimed at controlling hip and pelvic motion (proximal stability) and ankle/foot motion (distal stability) may be warranted and should be considered when treating persons with patellofemoral joint dysfunction. The purpose of this paper is to provide a biomechanical overview of how altered lower-extremity mechanics may influence the patellofemoral joint. By addressing these factors, better long-term treatment success and prevention may be achieved.

Intrinsic risk factors for the development of patellar tendinitis in an athletic population. A two-year prospective study

Retrospective studies have suggested various factors that might cause a disposition to develop patellar tendinitis, but no prospective data exist to determine any relationships. The purpose of this study was to determine the intrinsic risk factors for the development of patellar tendinitis in an athletic population. Before the study, 138 male and female students of physical education were evaluated for anthropometric variables, leg alignment characteristics, and muscle tightness and strength parameters. During the 2-year study, 19 of the 138 students developed patellar tendinitis. In all cases the diagnosis was confirmed by the presence of a hypoechogenic nodular lesion in the proximal region of the patellar tendon. Univariate and stepwise discriminant function analyses were performed comparing the various measurements. These analyses revealed that the only significant determining factor was muscular flexibility, with the patellar tendinitis patients being less flexible in the quadriceps and hamstring muscles (P < 0.05). The results of this study demonstrate that lower flexibility of the quadriceps and hamstring muscles may contribute to the development of patellar tendinitis in an athletic population. Therefore, the prevention of this condition in athletes should be focused on screening for and treating poor quadriceps and hamstring muscle flexibility.

Influence of Q-angle on lower-extremity running kinematics

STUDY DESIGN

Two-group posttest-only comparison.

OBJECTIVE

To assess the influence of the Q-angle on the 3-dimensional lower-extremity kinematics during running.

BACKGROUND

An excessive Q-angle has been implicated in the development of knee injuries by altering the lower-extremity locomotion kinematics. Previous investigations using 2-dimensional analyses during walking did not support this hypothesis.

METHODS AND MEASURES

We hypothesized that individuals with Q-angles more than 15 degrees would display an increase in rearfoot eversion and tibial internal rotation during running. Thirty-two nonimpaired subjects (men: n = 16, mean age = 22 +/- 3 years; women: n = 16, mean age = 23 +/- 3 years) ran over ground, and 3-dimensional kinematic data were collected from the right lower extremity. Subjects with a Q-angle of 15 degrees or less comprised the low-Q-angle group, whereas those with Q-angles of more than 15 degrees comprised the high-Q-angle group. Segment and joint maximum angles and the times when the maxima occurred during stance were measured.

RESULTS

The Q-angle magnitude did not increase the maximum segment or joint angles during running. The groups displayed similar maximum angles for rearfoot eversion (low Q-angle, -15.5 +/- 5.0 degrees; high Q-angle, -15.6 +/- 6.6 degrees) and tibial internal rotation (low Q-angle, -8.8 +/- 4.8 degrees; high Q-angle, -6.8 +/- 5.1 degrees). The high-Q-angle group (39.5 +/- 16.3%) achieved maximum tibial internal rotation later in the stance phase than the low-Q-angle group (28.8 +/- 10.7%).

CONCLUSIONS

In support of the previous investigations involving Q-angle influences on kinematics, our study did not reveal any differences between groups in maximum joint or segment angles. The kinematic information did reveal that the high-Q-angle group displayed an increase in time to maximum tibial internal rotation. The impact of this single factor on producing knee injury is unknown.

Effects of isometric quadriceps activation on the Q-angle in women before and after quadriceps exercise

STUDY DESIGN

Single-group test-retest design with correlation analysis.

OBJECTIVES

(1) To confirm that the Q-angle decreases with isometric quadriceps activation (IQA), (2) to determine if the decrease in the Q-angle with IQA is related to the magnitude of the Q-angle at rest, and (3) to determine if a vigorous bout of exercise affects the change in the Q-angle with IQA.

BACKGROUND

The Q-angle represents an estimate of the resultant force of the quadriceps on the patella and is a predictor of lateral movement of the patella under dynamic conditions.

METHODS AND MEASURES

Q-angles were assessed in 22 nonimpaired women (mean +/- SD age, 22.3 +/- 4.9 years) while standing relaxed and during IQA. Subjects then rode a cycle ergometer until a preset number of repetitions per minute was unable to be maintained. Q-angles were again assessed while subjects were relaxed and during IQA.

RESULTS

There was a significant decrease (mean +/- SD, 5.7 +/- 4.2 degrees) in the Q-angle with IQA compared with relaxed standing. There was a significant relationship (r=0.72) between the Q-angle at rest and the change with IQA. The cycle ergometer exercise resulted in a small (0.5 degrees) but significantly greater decrease in the Q-angle with IQA compared with relaxed standing.

CONCLUSIONS

The Q-angle decreases with IQA, and the magnitude of this decrease is dependent on the magnitude of the Q-angle at rest. Our findings support the view that an excessive Q-angle may predispose women to greater lateral displacement of the patella during vigorous activities and sports in which the quadriceps muscle is stressed.

Q-angle influences on the variability of lower extremity coordination during running

The quadriceps angle (Q-angle) has received attention as a possible predictor of patellofemoral pain (PFP). It has been suggested that an excessive Q-angle alters the patellofemoral tracking, thereby leading to PFP. Traditional methods used to evaluate alterations in lower extremity angular kinematics have not confirmed this thought. A dynamical systems approach involving segment couplings may provide additional insight by addressing the variability of the intersegmental coordination.

METHODS

Thirty-two healthy pain-free subjects with varying Q-angles were examined and divided into groups based on gender and Q-angle. Subjects ran overground for 10 trials while three-dimensional kinematic data were collected from the thigh, leg, and foot. The kinematic data were digitized and filtered before a direct linear transformation was employed to calculate three-dimensional segment angles and angular velocities. The variability of the continuous relative phase (CRP) of segment couplings was used to assess between-trial consistency at specific stance phase intervals.

RESULTS

No differences in CRP variability were found among subjects with varying Q-angles. Significant differences were present between the specific intervals of the couplings with the greatest variability during initial stance (P < 0.05).

CONCLUSIONS

A difference in CRP variability does not appear to exist in the lower extremity between individuals with and without abnormal Q-angles. The significant differences among the stance phase intervals of running suggest the inherent presence of coordination pattern variability. The importance of the increased pattern variability during initial stance may be associated with maintaining external stability.

Bilateral Q angle asymmetry and anterior knee pain syndrome

OBJECTIVE

To determine whether quadriceps (Q) angles were bilaterally symmetric in individuals asymptomatic vs symptomatic for anterior knee pain.

DESIGN

Cross-sectional study.

BACKGROUND

Previous attempts to link excessive Q angles to the occurrence of knee pain have yielded equivocal results. Deriving unilateral rather than bilateral measures of the Q angle and thereafter analysing data using traditional between-group analysis-of-variance structural models may, however, play a role in obscuring the true nature of the Q angle-knee pain relationship.

METHODS

Left and right Q angles were goniometrically measured in 75 subjects (37 males, 38 females) while they adopted a static, standing position with quadriceps relaxed. The majority (n = 50) were asymptomatic, while the remainder were unilaterally (n = 11) or bilaterally (n = 14) symptomatic for anterior knee pain. A questionnaire was used to determine the extent and magnitude of pain experienced in each of the symptomatic subjects.

RESULTS

Significant right vs left lower limb differences in Q angles were observed by group (p < 0.001) and group by gender (p < 0.05). Mean values, however, did not always reflect the true variation of data within the sample. Forty-seven percent of the subjects studied demonstrated a minimum 4 degrees bilateral Q angle difference, while in 13 of 75 subjects, this difference ranged from 8 degrees to 12 degrees. Only a weak yet significant relationship between right and left Q angles (r = 0.53, p < 0.001) was noted. While there were no correlations between Q angle measures and the magnitude of discomfort experienced in unilateral knee pain sufferers, these relationships were weak yet significant in bilateral knee pain sufferers.

CONCLUSION

Q angles are not bilaterally symmetric, with the magnitude and direction of the observed asymmetry varying according to whether an individual is asymptomatic, unilaterally symptomatic, or bilaterally symptomatic for anterior knee pain.

RELEVANCE

Future investigations of the Q angle must ensure that measures are derived bilaterally and analysed appropriately. Data from unilateral vs bilateral symptomatic subjects should be evaluated separately, and the shortcomings of standard ANOVA structural models must be recognized.

The quadriceps angle: a review of the literature

Previous investigations of the quadriceps (Q) angle and its relationship to knee disorders have yielded equivocal results. The purpose of this paper is to present a review of the current literature on the Q angle and to examine the differences in Q angles when measured: 1) under differing measurement protocols; 2) between asymptomatic and symptomatic populations; 3) between male and female samples; and 4) from side to side within subjects. Little scientific evidence exists to support the commonly held assumptions that Q angles are larger in symptomatic vs. asymptomatic or that they are equal in the right vs. left lower limb. However, larger mean values are consistently observed in groups of young adult females vs. young adult males.

Prevalence and morphology of the vastus medialis oblique muscle in human cadavers

BACKGROUND

The vastus medialis (VM) muscle has been described as being composed of two separate divisions: the vastus medialis longus (VML) proximally and the vastus medialis oblique (VMO) distally. The VML is reported to directly contribute to knee extension, while the VMO provides medial stabilization of the patella during knee extension. Despite the prevalence of literature describing the morphology and function of the VMO as an individual muscle, very little literature exists which actually substantiates the existence of the VMO as a separate, distinct muscle from the VML. The purpose of this study was to examine a sufficiently large sample of human cadavers to quantify and substantiate the existence of the VMO as a separate, distinct muscle from the VML, and to establish a statistical parameter representative of a normal adult population.

METHODS

Three hundred seventy-four adult human cadaver lower extremities were dissected, exposing the entire anterior thigh from the anterior superior iliac spine to the tibial tubercle. Examination of the cadavers included goniometric measurement of the fiber angles of the VML and VMO, determination of the existence and location of a fascial plane, and determination of the maximum VM fiber angle in all cadaver specimens. Descriptive statistics were performed on all fiber angle measurements and frequency of fascial plane presence. Analysis of variance was performed on the maximal VM fiber angle between muscles with and without a definitive fascial plane. Intrarater reliability tests were performed on all measures to ensure the reliability and increase the validity of all of the measurements taken.

RESULTS

A statistical parameter for the appearance of VMO features as originally defined was set at 21.65% of the sample. No statistically significant differences existed in the maximal VM fiber angle between the groups demonstrating the presence or absence of a VM fascial plane. None of the cadavers possessed an aponeurotic sheet of epimysium anatomically separating the VMO from the VML.

CONCLUSIONS

This study supports earlier research reporting a difference in fiber orientation between the proximal and distal VM fibers; however, contrary to statements in published literature, the VMO does not appear to be an anatomically separate structure from the VML inherent throughout the human population. The results of this study do not support the concept that the VMO and VML exist as anatomically separate structures in a sample of human cadavers.