Effect of taping the patella on concentric and eccentric torque and EMG of knee extensor and flexor muscles in patients with patellofemoral pain syndrome

The acute effect of patella taping on torque and electromyographic (EMG) activity in maximal voluntary concentric and eccentric action of the knee extensor and flexor muscles in patients with patellofemoral pain syndrome was studied in 48 patients (62 knees). The patients (28 female, 20 male) were tested concentrically and eccentrically on a Kin-Com dynamometer with simultaneous EMG recording with the patella untaped and medially or laterally taped. Patients with clinically normal patellar mobility did not improve their quadriceps performance by taping of the patella: after medial taping they decreased theur muscle torque during concentric work at 60°/s (P<0.05) and eccentric work at 180°/s (P<0.05). After lateral taping they decreased their muscle torque during concentric work at 60°/s (P<0.01), and 180°/s (P<0.05) and eccentric work at both 60°/s (P< 0.01) and 180°/s (P< 0.05). Moreover, these patients also decreased their agonist EMG activity during concentric work at 60°/s (P<0.05) and 180°/s (P<0.05) and their antagonist EMG activity during eccentric work at 60°/s (P<0.01). Patients with a clinical lateral patellar hypermobility increased their knee extensor torque after medial taping at 60°/s during both eccentric work (P<0.01) and concentric work (P<0.05). The greatest improvement in quadriceps performance, however, was in patients with a clinical medial patellar hypermobility. They increased their knee extensor torque after lateral taping during eccentric work at both 60°/s (P<0.001) and 180°/s (P<0.001) and during concentric work at 60°/s (P<0.001). They also increased agonist EMG activity during eccentric work at both 60°/s (P<0.01) and 180°/s (P<0.001) and during concentric work at 180°/s (P<0.05). Patients with both lateral and medial patellar hypermobility increased their knee extensor torque by patellar taping in either direction; after medial taping there was an increase during eccentric work at both 60°/s (P<0.01) and 180°/s (P<0.05) and after lateral taping they also showed an increase during eccentric work at 60°/s (P<0.01). There was a slight decrease in knee flexor torque with either medial or lateral taping in comparison with no taping. Furthermore, there was higher antagonist EMG activity during hamstring measurements when the patella was either medially or laterally taped as opposed to untaped. In all four groups of patients, except for the group with lateral and medial hypermobility, there was a highly significant correlation between patients' own evaluation of the taping and their patellar mobility according to the clinical examination.This study was supported by grants from the Swedish Sports Federation and from Beiersdorf Compancy, Homburg, Germany     

Isokinetic quadriceps training in patients with patellofemoral pain syndrome

The aims of the present investigation were (a) to evaluate the effect of eccentric quadriceps training in patients with unilateral patellofemoral pain and (b) to compare the effect of eccentric and concentric quadriceps training in patients with bilateral patellofemoral pain. Fifteen patients (9 male and 6 female, aged 17–36 years with a mean of 27.5 years) participated in this study. Nine patients had unilateral pain and trained their painful leg eccentrically, while six had bilateral pain and trained one leg eccentrically and the other concentrically. Quadriceps muscle training was performed on a Kin-Com dynamometer at 90°/s and 120°/s angular velocity twice a week for 8 weeks. Before and after the treatment period the thigh muscle torques were measured on the Kin-Com dynamometer at 60°/s, 90°/s, 120°/s and 180°/s for quadriceps and at 60°/s and 180°/s for hamstrings. Nine controls, matched for gender and age with the group with unilateral pain, were tested in the same way on the Kin-Com dynamometer. For functional evaluation a knee score was calculated before training, after 8 weeks of training and at a mean of 3.4 years after completion of the training. After 8 weeks of training and at follow-up times of 1 and 3.4 years the patients were also questioned regarding whether or not they felt improvement from the training programme. To determine the degree of knee pain during the training Borg's pain scale was used. The results showed that, compared with the controls, the patients had a significantly lower knee extensor torque in their painful leg at all velocities measured. The greatest difference was found during eccentric actions. However, in comparison with the controls there were no significant differences in eccent ic and concentric knee flexor torques. After training there was a significant increase particularly in eccentric but also in concentric torque of the knee extensor in the painful leg of the eccentrically trained group. Of the six patients in the bilateral training group there were five who increased their concentric knee extensor torque and three who increased their eccentric torque. There were no significant differences in concentric and eccentric knee flexor torques before and after training in either of the legs in both training groups. The hamstring/quadriceps ratio was significantly higher in the patients' painful leg before training. However, due to increased quadriceps strength the hamstring/quadriceps ratio dropped after training. Patients in both groups reported no pain or mild pain during the training sessions. The eccentrically trained group was significantly improved both after 8 weeks of treatment and at follow-up 3.4 years later as evaluated using the knee score. The bilaterally trained group was significantly improved 3.4 years after completion of the training programme as evaluated using the knee score.     

Relationship among eccentric hip and knee torques, symptom severity and functional capacity in females with patellofemoral pain syndrome

Objective

To determine the relationships between eccentric hip and knee torques, symptom severity and functional capacity in females with patellofemoral pain syndrome (PFPS).

Design

Within-subject correlational study.

Setting

University biomechanics laboratory.

Participants

10 females diagnosed with PFPS.

Main outcome measures

Eccentric strength of the hip abductors and lateral rotators, and knee extensors were assessed using an isokinetic dynamometer. A 10-cm visual analog scale was used to determine usual knee pain in the last week. The Anterior Knee Pain Scale (AKPS) was used to determine the functional capacity of the patients.

Results

The study found that the greater the eccentric knee extensor and hip lateral rotator torques, the higher the functional capacity of the patients (p = 0.02, r = 0.72; p = 0.02, r = 0.72). It was also shown that the greater hip lateral rotator torque, the less the usual pain reported in the last week (p = 0.004, r = −0.84). Despite the lack of statistical significance (p = 0.11), it was also found a modest negative relationship between the eccentric knee extensor torque and the usual pain reported in the last week (r = −0.56) that was considered clinically meaningful (d = 1.4).

Conclusions

This study showed that eccentric knee extensor and hip lateral rotator torques were associated with functional capacity and pain level in females with PFPS. Further investigations should be carried out to verify the effects of an intervention program focused on the eccentric action of these muscles with respect to the symptoms in patients with PFPS.     

Patellofemoral morphometry in patients with idiopathic patellofemoral pain syndrome

Purpose

To compare clinical and computed tomography (CT) measures in extension, 20° and 30° of flexion of symptomatic knees of patient with idiopathic patellofemoral pain syndrome with the contra lateral asymptomatic knee.

Materials and methods

Knees of 52 consecutive patients with idiopathic patellofemoral pain were studied with CT. In 28 patients this condition was unilateral and asymptomatic knee was used as control; 76 knees were symptomatic.

Results

In patients with idiopathic patellofemoral pain we found a greater Q angle and internal condylar facet width in symptomatic knees with regard to asymptomatic knees.

Conclusion

Greater Q angle and medial condylar facet can lead to overpressure on the medial knee compartment during maneuvers that increase contact between patella and medial condylar facet, such as knee flexion and squatting, contributing to development of idiopathic patellofemoral pain.     

Personality in patients with long-term patellofemoral pain syndrome

Personality characteristics in patients with long-term patellofemoral pain were compared to those of matched controls and other groups both of non-patients and of psychiatric outpatients with character disorders. Personality was described using the self-administered dependency and alexithymia scales, the Karolinska Scales of Personality and the Rorschach inkblot method. The hypothesis was that the patellofemoral pain patients would have higher levels of anxiety, depression, helplessness, aggression and alexithymic characteristics than the matched controls. There were only a few significant differences between the knee patients and the matched controls. The Rorschach measures suggested significantly greater depression, hostility and passive attitude in the knee patients as compared to the reference data. There were no indications of the hypothesised alexithymic characteristics in the knee patients. If patellofemoral pain patients do not improve as expected, referral to a pain clinic with psychological expertise could be considered.     

Trunk,pelvis, and knee kinematics during running in females with and without patellofemoral pain

BackgroundFemales are two times more likely to develop patellofemoral pain (PFP) than males. Abnormal trunk and pelvis kinematics are thought to contribute to the pathomechanics of this condition. However, there is a scarcity of evidence investigating proximal segments kinematics in females with PFP.Research questionThe purpose of this study was to investigate whether females with PFP demonstrate altered trunk, pelvis, and knee joint kinematics compared with healthy controls during running.MethodsThirty-four females (17 PFP, 17 controls) underwent a 3-dimensional motion analysis during treadmill running at preferred and fixed speeds, each trial for 30 s. Variables of interest included magnitudes of peak angles for trunk (forward flexion, ipsilateral trunk lean), pelvis (anterior tilt, contralateral drop), knee (flexion, valgus, internal rotation), range of motion (RoM) of trunk and pelvis in sagittal and frontal planes and RoM of knee joint in the three cardinal planes of motion. Kinematic data were compared between groups using mixed model repeated measure analysis of variance with the trial as the repeated measure.ResultsThe PFP group displayed significantly less pelvis frontal plane RoM, greater knee frontal plane RoM, and less knee sagittal plane RoM during running compared with controls, irrespective of running trial. No differences were found in peak kinematic variables between PFP and healthy groups.SignificanceThese results may suggest a rigid stabilization strategy at the pelvis, which the body has adapted to prevent further frontal plane knee malalignment. Less knee sagittal plane RoM may be indicative of another protective strategy in the PFP group to avoid patellofemoral joint reaction force. Clinical assessments and rehabilitative treatments may benefit from considering a global program with focus on pelvis kinematics in addition to the knee joint in females with PFP.     

Kinematic and electromyographic analysis in patients with patellofemoral pain syndrome during single leg triple hop test

Possible delays in pre-activation or deficiencies in the activity of the dynamic muscle stabilizers of the knee and hip joints are the most common causes of the patellofemoral pain syndrome (PFPS). The aim of the study was to compare kinematic variables and electromyographic activity of the vastus lateralis, biceps femoris, gluteus maximus and gluteus medius muscles between patients with PFPS and health subjects during the single leg triple hop test (SLTHT). This study included 14 female with PFPS (PFPS group) and 14 female healthy with no history of knee pain (Healthy group). Kinematic and EMG data ware collected through participants performed a single session of the SLTHT. The PFPS group exhibited a significant increase (p < 0.05) in the EMG activity of the biceps femoris and vastus lateralis muscles, when compared with the healthy group in pre-activity and during the stance phase. This same result was also found for the vastus lateralis muscle (p < 0.05) when analyzing the EMG activity during the eccentric phase of the stance phase. In kinematic analysis, no significant differences were found between the groups. These results indicate that biceps femoris and vastus lateralis muscles mainly during the pre-activation phase and stance phases of the SLTHT are more active in PFPS group among healthy group.     

Foot exercises and foot orthoses are more effective than knee focused exercises in individuals with patellofemoral pain

ObjectivesTo examine the effect of knee targeted exercises compared to knee targeted exercises combined with foot targeted exercises and foot orthoses in patients with patellofemoral pain.DesignForty adult individuals (28 women, 12 men) diagnosed with patellofemoral pain and screened for excessive calcaneal eversion were randomized to knee targeted exercises or knee targeted exercises combined with foot targeted exercise and orthoses.MethodsThe knee targeted exercises were prescribed during three supervised consultations. Individuals were instructed to perform the exercises 3 times per week during a 12-week period. The foot targeted exercises were prescribed for 2 times per week for 12 weeks with one session per week being supervised by a physiotherapist. The primary outcome was the subscale “pain” in the Knee Injury and Osteoarthritis Outcome Score (KOOS) at 4 months.ResultsIndividuals randomized to knee targeted exercises combined with foot targeted exercises and foot orthoses had 8.9 points (95%CI: 0.4; 17.4) – NNT = 3 (2–16) larger improvement in KOOS pain at the primary endpoint.ConclusionsThe addition of foot targeted exercises and foot orthoses for 12 weeks was more effective than knee targeted exercises alone in individuals with patellofemoral pain. The effect was apparent after 4 months, but not significantly different after 12 months.     

The role of patellar alignment and tracking in vivo: The potential mechanism of patellofemoral pain syndrome

Purpose and method

Lateral patellar malalignment and maltracking are commonly believed to be associated with patellofemoral pain. In the current review, a computerized and manual search of English-language articles was performed using multiple combinations of the following keywords: ‘patellofemoral pain syndrome’ or ‘patellofemoral pain’, and ‘patellar alignment’ or ‘patellar tracking’. The role of patellar alignment and tracking in vivo is discussed via a review of papers regarding the differences in asymptomatic and symptomatic patella. An attempt is made to identify the potential mechanism of patellofemoral pain syndrome (PFPS).

Conclusion

Evidence suggests that symptomatic patella do not consistently demonstrate lateral malalignment or tracking in patellar tilt and translation. Abnormal patellar alignment and tracking may be potential risk factors that are associated with patellofemoral pain. Other contributing factors should be considered in dealing with patellofemoral pain syndrome. Further studies are required to determine what normal patella alignment and tracking is before going on to define how these are altered in subjects with patellofemoral pain. Furthermore, prospective studies are needed to identify the alteration of patellofemoral kinematics, if any, and whether these are the causative factor or the consequence of the patellofemoral pain syndrome, as well as to determine the risk of development of patellofemoral pain syndrome in individuals with and without abnormal patellar tracking.     

The effects of McConnell patellofemoral joint and tibial internal rotation limitation taping techniques in people with Patellofemoral pain syndrome

BackgroundTaping is frequently used as part of the multi-modal management for patellofemoral pain syndrome (PFPS). McConnell Patellofemoral Joint Taping (PFJT) and Tibial Internal Rotation Limitation Taping (TIRLT) are proposed to be useful adjuncts to the management of PFPS. However, it is unclear if TIRLT offers similar benefits to PFJT, and its effect on pain and lower limb kinematics have not been investigated previously.Research questionWhat are the effects of TIRLT, PFJT and no taping on perceived pain and lower limb kinematics during a lunge and single leg squat (SLS) in people with PFPS?MethodsThis cross-sectional study compared the effects of TIRLT, PFJT and no taping, on knee pain and lower limb kinematics during two pain-provoking movements in people with PFPS. Participants with PFPS (n = 23) performed a lunge and SLS under three randomised conditions: TIRLT, PFJT and no taping. The Codamotion system captured and analysed lower limb kinematic data in the sagittal, transverse and coronal planes. Peak knee pain intensity during the movement was assessed using the Numerical Rating Scale (NRS).ResultsParticipants reported significantly less pain with the TIRLT and PFJT techniques compared with no tape during the lunge (p = 0.005 and p = 0.011, respectively) and SLS (p= 0.002 and p = 0.001, respectively). There was no evidence of altered lower limb kinematics accompanying pain reductions with either taping technique.SignificanceBoth forms of taping may be useful adjuncts as the short-term benefit of pain relief may enable participation in more active forms of rehabilitation.     

Decrease of knee flexion torque in patients with ACL reconstruction: combined analysis of the architecture and function of the knee flexor muscles

A decrease of deep knee flexion torque after anterior cruciate ligament (ACL) reconstruction, using a semitendinosus (and gracilis) tendon, has been reported. However, the cause of this weakness remains controversial. Architectural and functional differences in the knee flexor muscles influence this weakness. the fiber length of the semitendinosus, gracilis, semimembranosus, and biceps femoris were directly measured in six human cadavers. The flexion torque and EMG of the hamstrings were measured in both limbs of 16 patients (23±5 years) after ACL reconstruction (12–43 months post-operation), using ipsilateral semitendinosus tendon. Magnetic resonance imagings were taken, over both the thighs of those patients, to measure muscle volume and to confirm a state of semitendinosus tendon regeneration. The position of the musculotendinous junction of the semitendinosus was also analyzed. The fiber length of the semitendinosus and gracilis were three to four times longer than that of the semimembranosus and biceps femoris. The difference of flexion torque between the normal and ACL reconstructed limbs significantly increased as the knee flexion angle increased. The EMG value for the semimembranosus and biceps femoris of both limbs as well as the semitendinosus of the ACL reconstructed limbs, significantly reduced as the knee flexion angle was increased. The volume of the semitendinosus in the reconstructed limb was significantly smaller than in normal limbs. The regeneration of the semitendinosus tendon was confirmed in all subjects, and the musculotendinous junction position of the reconstructed limb in almost all subjects was found in further image from the knee joint space than that for the normal limb. The decrease of deep knee flexion torque, after ACL reconstruction, could be due to the atrophy and shortening of the semitendinosus after its tendon has been harvested, as well as the lack of compensation from the semimembranosus and biceps femoris, due to the architectural differences between the semitendinosus and the semimembranosus and biceps femoris.     

Patellar bracing affects sEMG activity of leg and thigh muscles during stance phase in patellofemoral pain syndrome

BackgroundDecreases in patellofemoral pain symptoms with bracing treatment have been established; but, the mechanisms remain unclear. The purpose of this study was to determine the immediate and long-term effects of the patellar bracing on electromyography (EMG) activity of the Vastus Medialis (VM) and Lateralis (VL), Rectus Femoris, lateral Gastrocnemius, Biceps Femoris and Semitendinosus (ST) muscles during level walking.Methods12 eligible women aged 20–30 years with diagnosis of patellofemoral pain participated in the before and after study. Intervention consisted of 8 weeks of patellar bracing. First, patients were tested without brace, then with a brace, and finally eight weeks later without a brace. Surface EMG activation of the selected muscles during level walking was recorded.ResultsAfter eight weeks of patellar bracing, EMG activity of VM muscle was significantly higher when compared to first session without brace (p = 0.011) at mid-stance sub-phase. Additionally, EMG activity of ST muscle during first session with brace was significantly lower when compared to first session without brace at mid-stance sub-phase (without brace) (p = 0.012). EMG activity of VM muscle after eight weeks of patellar bracing was significantly higher than the first session without brace at late stance and preswing sub-phase (p = 0.013).ConclusionLong-term wearing of patellar bracing increases EMG activity of VM during mid-stance and late stance and preswing sub-phases of gait and immediate effect of patellar brace is decrease of EMG activity of ST muscle during mid-stance.     

CT determination of tibial tubercle lateralization in patients presenting with anterior knee pain

Anterior knee pain is commonly associated with patellofemoral malalignment. Both conventional radiographic measurements and CT measurements have been proposed to define and confirm the sometimes difficult clinical diagnosis of anterior knee pain secondary to patellofemoral malalignment. Using CT imaging with computerized technique to measure anatomic relationships, we evaluated patients (n=50) with anterior knee pain for excessive lateralization of the tibial tubercle. The symptomatic knee of each patient was compared with their asymptomatic knee as well as with the knees of patients with other causes of anterior knee pain (n=10) and with the knees of asymptomatic controls (n=10). The symptomatic knee of patients with suspected patellofemoral malalignment demonstrated significantly greater lateralization of the tibial tubercle (12.2±0.5 mm) than did the asymptomatic knee (9.0±0.7 mm). The symptomatic knees of patients with patellofemoral malalignment also demonstrated significantly greater lateralization of the tibial tubercle than did the knees of patients with other causes of anterior knee pain (5.9±0.9 mm). When a control population was added to the analysis, the patients with symptomatic patellofemoral malalignment demonstrated significantly greater lateralization of the tibial tubercle than did the controls (6.4±0.4 mm). Using a critical value of 9 mm lateralization, the CT diagnosis of patellofemoral malalignment had a specificity of 95% and a sensitivity of 85%. We conclude that CT determination of tibial tubercle position assists the diagnosis of patellofemoral malalignment.     

Internal and external focus show similar effect on the gait kinematics in patients with patellofemoral pain: A randomised controlled trial

PurposeThe purpose of this study was to examine how attentional focus during training influences the effects of a 6-week hip-knee strength training program on pain, function, strength, and kinematics in males and females with Patellofemoral pain (PFP).MethodsSeventy-five males and females with PFP were randomly allocated to a group that trained with an internal focus (n = 25), a group that trained with an external focus (n = 25), or a control group (n = 25). All patients completed testing before (baseline) and after (posttest) the 6-week period. The primary outcome was pain, assessed by Visual Analog Scale (VAS). The secondary outcomes were function, hip muscles strength and lower extremity kinematics, assessed by Kujala Questionnaire, handheld dynamometer and a 2-D motion capture, respectively. All outcomes were measured at the baseline and after the 6-week intervention. Analysis of covariance was used to compare posttest outcomes among the groups while accounting for group differences in baseline performance.ResultsThe hip-knee strengthening exercises resulted in improved knee valgus (ES(95 % CI) = 0.43(0.26 to 0.75), p = 0.03), and external rotator strength (ES(95 % CI) = 0.51(0.12 to 0.78), p = 0.03) for males and females who trained with an external compared to internal focus.ConclusionsOur findings indicate that males and females with PFP may benefit from completing a hip-knee strengthening training program with an external focus vs. an internal focus. Physical therapists and clinicians should consider using instructions that promote an external focus when implementing hip-knee strengthening training programs with PFP patients. This result could be strengthened or re-enforced by larger studies with longer follow up.     

Kinematics and muscle forces in women with patellofemoral pain during the propulsion phase of the single leg triple hop test

BackgroundApproximately 25% of orthopedic knee conditions are related to patellofemoral pain (PFP), with young women being the most affected. It is thought that this condition is associated with modifications in the kinematics and muscle control patterns of the lower limb during weight-bearing support activities, which increases femur movement under the patella.ObjectivesTo compare kinematics and muscle induced acceleration patterns between PFP subjects and healthy controls during the preparation phase of the single leg triple hop test.Study designBiomechanical analysis was performed using OpenSim. Ten physically active women (23.2 ± 4 years, 59.3 ± 5.8 kg, and 1.63 ± 0.06 m) with no history of lower limb injury (CG) and 11 volunteers (23.5 ± 2 years, 55.4 ± 4.9 kg, and 1.66 ± 0.04 m) with PFP (PFPG) were recruited. The participants performed a series of single leg triple hop tests while the ground reaction forces and kinematic data were recorded.ResultsVector field statistical analysis indicated increased lumbar extension, anterior pelvic tilt, contralateral pelvic drop, and lower induced accelerations from the core and hip muscles in PFPG.ConclusionPFP volunteers presented with alterations in lumbar muscle control associated with a possible compensatory pelvic strategy to minimize knee extensor moment.     

Knee flexor strength and rate of torque development deficits in women with patellofemoral pain are related to poor objective function

BackgroundDeficits in knee flexor strength and rate of torque development (RTD) might be present in women with patellofemoral pain (PFP). In addition, maximal strength and RTD of the knee flexors and extensors might be related with subjective and objective function in women with PFP. However, both conjectures are still poorly understood.Research questionDo women with PFP have deficits in the maximal strength and RTD of the knee flexors and extensors during isometric, concentric, and eccentric contractions? Is there a relationship between maximal strength and RTD of the knee flexors and extensors with subjective and objective function in women with PFP?MethodsFifty-six women with, and 46 women without, PFP participated. Maximal strength and RTD (to 30% and 60% maximal torque) during isometric, concentric, and eccentric contractions of the knee flexors and extensors were assessed using an isokinetic dynamometer. Objective assessment included single leg hop test (SLHT) and forward step-down test (FSDT). Subjective assessment involved the anterior knee pain scale.ResultsWomen with PFP had small to large deficits in maximal strength and RTD of the knee flexors and extensors during isometric, concentric and eccentric contractions (Effect sizes: -0.43 to -1.10; p ≤ 0.016). Small to moderate correlations of maximal concentric and eccentric knee flexor strength and RTD with SLHT and FSDT (r = 0.28 to 0.41; p ≤ 0.037) were identified. Subjective or objective function were not correlated with maximal isometric knee flexor strength and RTD, or any knee extensor measures (p > 0.05).SignificanceMaximal strength and RTD deficits of the knee flexors and extensors were identified in this female PFP cohort, but they were unrelated to subjective function. The relationship of concentric and eccentric knee flexor strength and RTD deficits with poor objective function should be considered in future exercise trials for women with PFP.     

Distribution of substance-P nerve fibers in the knee joint in patients with anterior knee pain syndrome A preliminary report

The etiology of pain in anterior knee pain syndrome is a matter of controversy. The normal, articular cartilage is aneural, so defects in the surface are not thought to produce pain. Some authors have sought the origin of the pain in soft tissue structures around the knee. Knowledge of the distribution of nociceptive nerve fibers around the knee would provide insight for treating anterior knee pain syndrome. Twenty consecutive patients (28 knees), all women, with anterior knee pain syndrome (group I) participated in the study. For comparison we used two groups of patients: 20 patients with an osteoarthritic knee (group II) and 20 patients with anterior cruciate ligament rupture or meniscal lesion with no history of pain in the anterior compartment (group III). Immunohistochemical techniques using a monoclonal antibody to substance-P (SP) were employed to identify nociceptive fibers. For statistical analyses we used the one-way ANOVA test, which was corrected with the LSD test, at the level of significance P < 0.05. Results of the study demonstrate that SP-immunoreactive nerve fibers are widespread within the soft tissues around the knee. These tissues include the retinaculum, synovium, fat pad and, in some circumstances, bone. In cases of anterior knee pain, the presence of neuropeptide-containing fibers was statistically significant in the medial retinaculum (P < 0.005) and in the fat pad (P < 0.001) compared to group III, and compared to group II (P < 0.05 and P < 0.007, respectively). For lateral retinaculum this relationship was not so statistically strong (P < 0.02) and was equal in comparison between anterior knee pain patients (group I) and group II or group III. There were no statistically significant differences in the distribution of substance-P nerve fibers in the fat pad, lateral and medial retinaculum or synovium between groups II and III. The results of this study provide immunohistochemical evidence suggesting that pain may originate in the fat pad and medial retinaculum of many patients with anterior knee pain syndrome. Received: 17 December 1997 Accepted: 20 October 1998     

Knee flexor strength,rate of torque development and flexibility in women and men with patellofemoral pain: Relationship with pain and the performance in the single leg bridge test

ObjectivesTo investigate the relationship between: (1) knee flexor strength, rate of torque development (RTD), and flexibility with pain level; (2) knee flexor strength and RTD with the performance in the single leg bridge test (SLBT) in women and men with patellofemoral pain (PFP).DesignCross-sectional.SettingLaboratory-based study.Participants39 women and 36 men with PFP.Main outcome measuresKnee flexor strength, RTD, and flexibility; performance in the SLBT, current, and worst pain level.ResultsModerate to strong significant negative relationships were identified between the current pain level with knee flexor strength (r = −0.57 to −0.34) and flexibility (r = −0.44 to −0.35); and between knee flexor strength and RTD with the performance in the SLBT (r = 0.34 to 0.57) in women and men with PFP. Knee flexor RTD was not related to any pain level and no significant relationships were identified between the worst pain level with knee flexor strength and flexibility in women and men with PFP.ConclusionsOur results support the potential value of assessing knee flexor strength and flexibility in women and men with PFP. The SLBT may be a useful tool to assess knee flexor muscle capacity in individuals with PFP in a clinical setting.     

Is the degree of osteophyte formation associated with the symptoms and functions in the patellofemoral joint in patients undergoing total knee arthroplasty?

Osteophyte formation and loss of articular cartilage are the main pathologic features of osteoarthritis in the patellofemoral joint. The goal of this study was to determine whether the degree of osteophyte formation was associated with the degree of cartilage loss and the patellofemoral symptoms and functions in osteoarthritic patients undergoing total knee arthroplasty (TKA). We evaluated 71 knees in 54 consecutive patients who underwent TKA under the diagnosis of osteoarthritis. The degree of patellofemoral osteophyte formation was assessed by proportional diameter and proportional rim involvement. The cartilage status was assessed by depth and size of the cartilage lesion. The patellofemoral symptoms and functions included anterior knee pain, abilities of chair-rising and stair-climbing and quadriceps muscle power. No significant association was found between the degrees of patellar or trochlear osteophyte formation with anterior knee pain or any of the patellofemoral functional parameters (P > 0.05). The degree of osteophyte formation in the patella and the trochlea had a significant but weak correlation with the status of patellar cartilage and the status of the trochlear cartilage, respectively (correlation coefficient = 0.22–0.41 and P < 0.05). This study indicates that physicians need to be cautious not to easily reach the conclusion that the patellofemoral symptoms and functional disabilities can be attributed to the presence of osteophyte in the patellofemoral joint in consulting patients with the patellofemoral radiographs or deciding on patellar resurfacing in TKA.