Youri Thijs

A Prospective Study on Gait-related Intrinsic Risk Factors for Patellofemoral Pain

Objective:To prospectively determine gait-related risk factors for patellofemoral pain. Design:A prospective cohort study. Setting:Male and female recruits of the Belgian Royal Military Academy during a 6-week basic military training period. Participants:Eighty-four officer cadets (65 men, 19 women), who entered the Military Academy and were without a history of any knee or lower-leg complaints, participated in the study. Interventions:Before the start of the 6-week basic military training period, plantar pressure measurements during walking were performed. During the basic military training period, patellofemoral complaints were diagnosed and registered by a sports medicine physician. Main Outcome Measurements:Plantar pressure measurements during walking were performed using a footscan pressure plate (RsScan International). Results:During the 6-week training period, 36 subjects developed patellofemoral pain (25 male and 11 female). Logistic regression analysis revealed that subjects who developed patellofemoral pain had a significantly more laterally directed pressure distribution at initial contact of the foot, a significantly shorter time to maximal pressure on the fourth metatarsal, and a significantly slower maximal velocity of the change in lateromedial direction of the center of pressure during the forefoot contact phase. Conclusions:Our findings suggest that the feet of the persons who developed anterior knee pain have a heel strike in a less pronated position and roll over more on the lateral side compared with the control group. The results of this study can be considered valuable in identifying persons at risk for patellofemoral pain.

Gait-related intrinsic risk factors for patellofemoral pain in novice recreational runners

Objective: To determine prospectively gait-related intrinsic risk factors for patellofemoral pain (PFP) in a population of novice recreational runners. Design: Prospective cohort study. Participants: 102 novice recreational runners (89 women) with no history of knee or lower leg complaints. Interventions: The standing foot posture of the subjects was examined and plantar pressure measurements during running were collected. The subjects then participated in a 10-week “start to run” programme. During this period all sports injuries were registered by a sports medicine physician. Main outcome measurements: The relationship between the standing foot posture and PFP was investigated and gait-related intrinsic risk factors for PFP were determined. Results: The 17 runners who developed PFP exerted a significantly higher vertical peak force underneath the lateral heel and metatarsals 2 and 3. Logistic regression analysis showed that a significantly higher vertical peak force underneath the second metatarsal and shorter time to the vertical peak force underneath the lateral heel were predictors for PFP. No significant evidence was found for an association between an excessively pronated or supinated foot posture and the development of PFP. Conclusions: The findings suggest that an excessive impact shock during heel strike and at the propulsion phase of running may contribute to an increased risk of developing PFP. The hypothesis that persons at risk for PFP show an altered static foot posture in comparison with non-afflicted persons is not supported by the results of this study.

Is Hip Muscle Weakness a Predisposing Factor for Patellofemoral Pain in Female Novice Runners? A Prospective Study

Background: Hip muscle weakness has been proposed to contribute to patellofemoral malalignment and the development of the patellofemoral dysfunction syndrome (PFDS). However, from the retrospective studies that have addressed this issue, it is still unclear if hip muscle weakness is a cause or a consequence of PFDS. Purpose: This study was undertaken to investigate if hip muscle weakness is a predisposing factor for the development of PFDS. Study Design: Cohort study (prognosis); Level of evidence, 2. Methods: Before the start of a 10-week “start to run” program, the isometric strength of the hip flexor, extensor, abductor, adductor, and external and internal rotator muscles was measured in 77 healthy female novice runners. During the 10-week training period, patellofemoral pain was diagnosed and registered by an orthopaedic surgeon. Results: Statistical analysis revealed that there was no significant difference in strength of any of the assessed hip muscle groups between the runners who did and did not develop PFDS. Logistic regression analysis did not identify a deviation in strength of any of the assessed hip muscle groups as a risk factor for PFDS. Conclusion: The findings of this study suggest that isometric hip muscle strength might not be a predisposing factor for the development of PFDS.

Relationship between hip strength and frontal plane posture of the knee during a forward lunge

Objective: Excessive frontal plane knee movement during forward lunge movements might be associated with the occurrence of knee injuries in tennis. Here, we attempt to determine whether hip muscle strength is related to the frontal plane motion of the knee during a functional lunge movement. Design: A correlational study. Participants: A total of 84 healthy subjects (76 men, 8 women), with no history of knee or lower leg complaints. Interventions: Muscle strength of six hip muscle groups was measured using a handheld dynamometer. Subjects were videotaped during a forward lunge and peak knee valgus or varus angles were determined using a digital video analysis software program. Main outcome measurements: A correlation was examined between hip muscle strength and the amount of frontal plane movement of the knee during a forward lunge. Results: There were no significant differences in hip muscle strength between the valgus group and the varus group during the forward lunge movement. No significant correlation was found between the strength of the assessed hip muscles and the amount of movement into valgus/varus. In the varus group a moderate positive correlation was found between the External Rotation/Internal Rotation force ratio and the amount of knee varus during the forward lunge movement (r = 0.31, p = 0.03). Conclusions: The findings suggest that in healthy subjects hip muscle strength is not correlated to the amount of valgus/varus movement of the knee during a forward lunge. This suggests that other factors (eg, proprioception, core hip stability) might be more important in controlling knee movement during this tennis-specific movement.

Balance, gait, falls, and fear of falling in women with the hypermobility type of Ehlers-Danlos syndrome

To investigate balance, gait, falls, and fear of falling in patients with the hypermobility type of Ehlers‐Danlos syndrome (EDS‐HT).

Medication, Surgery, and Physiotherapy Among Patients With the Hypermobility Type of Ehlers-Danlos Syndrome

OBJECTIVES To describe medication use, surgery, and physiotherapy, and to examine the effect of these treatment modalities on functional impairment and amount of complaints among patients with the hypermobility type of Ehlers-Danlos syndrome (EDS-HT). DESIGN Cross-sectional study. SETTING Physical and rehabilitation medicine department and center for medical genetics. PARTICIPANTS Patients with EDS-HT (N=79; 8 men, 71 women) were recruited for this study. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Patients filled out questionnaires regarding type of complaints, medication use, surgery, physiotherapy, and outcome of treatment. Functional impairment in daily life was measured by the Sickness Impact Profile. Pain severity was assessed with visual analog scales. RESULTS Patients reported a large number of complaints, a considerable presence of severe pain, and a clinically significant impact of disease on daily functioning. Most patients (92.4%) used medications, among which analgesics were the most prevalent. Fifty-six patients (70.9%) underwent surgery, including mainly interventions of the extremities and abdomen. Forty-one patients (51.9%) are currently enrolled in a physical therapy program, mainly comprising neuromuscular exercises, massage, and electrotherapy. Patients with a high consumption of analgesics, who visited the physiotherapist, or who underwent surgery had a higher dysfunction in daily life. Only 33.9% of the patients who underwent surgery and 63.4% of patients in physical therapy reported a positive outcome. CONCLUSIONS Patients with EDS-HT have numerous complaints and an impaired functional status that strongly determine their high rate of treatment consumption. The outcome of surgical and physiotherapy treatment is disappointing in a large percentage, which illustrates a strong need for evidence-based therapy.

Vastus Medialis Obliquus Atrophy: Does It Exist in Patellofemoral Pain Syndrome?

Background: Quadriceps atrophy and in particular atrophy of the vastus medialis obliquus (VMO) muscle have been frequently related with patellofemoral pain syndrome (PFPS), despite very little objective evidence. Hypothesis: Patients with PFPS exhibit atrophy of the VMO in comparison with healthy controls. Study Design: Case-control study; Level of evidence, 3. Methods: Forty-six patients with PFPS and 30 healthy control persons with similar age, gender, body mass index, and activity index distributions underwent magnetic resonance imaging (MRI) of the quadriceps. The muscle size was determined by calculating the cross-sectional area of the total quadriceps and its components. Results: The cross-sectional area (CSA) of the VMO was significantly smaller in the PFPS group than in the control group (16.67 ± 4.97 cm2 vs 18.36 ± 5.25 cm2) (P = .040). A tendency was noted for a smaller total quadriceps CSA for the PFPS patients at midthigh level (66.99 ± 15.06 cm2 vs 70.83 ± 15.30 cm2) (P = .074). Conclusion: This is the first study to examine VMO size in PFPS patients by MRI. Patients with patellofemoral problems exhibited atrophy of the VMO. Although it is not clear whether this atrophy is a result or a cause of PFPS, the results of this study do show that atrophy of the VMO is a contributing factor in PFPS. Longitudinal, prospective studies are needed to establish the cause-effect relation of VMO atrophy and PFPS.

Muscle mass, muscle strength, functional performance, and physical impairment in women with the hypermobility type of Ehlers-Danlos syndrome

To investigate lower extremity muscle mass, muscle strength, functional performance, and physical impairment in women with the Ehlers‐Danlos syndrome hypermobility type (EDS‐HT).

Does bracing influence brain activity during knee movement: an fMRI study

Studies have shown that proprioceptive inputs during active and passive arm movements are processed in the primary and secondary somatosensory cortex and supplementary motor area of the brain. At which level of the central nervous system proprioceptive signals coming from the knee are regulated remains to be elucidated. In order to investigate whether there is a detectable difference in brain activity when various proprioceptive inputs are exerted at the knee, functional magnetic resonance imaging (fMRI) was used. fMRI in 13 healthy, right leg-dominant female volunteers compared brain activation during flexion–extension movements of the right knee under three different conditions: with application of a tight knee brace, with application of a moderate tight knee sleeve, and without application of a brace or sleeve. Brain activation was detected in the primary sensorimotor cortex (left and right paracentral lobule) and in the left superior parietal lobule of the brain. There was a significantly higher level of brain activation with the application of the brace and sleeve, respectively, compared to the condition without a brace or sleeve. A significantly higher cortical activation was also seen when comparing the braced condition with the condition when a sleeve was applied. The results suggest that peripheral proprioceptive input to the knee joint by means of a brace or sleeve seems to influence brain activity during knee movement. The results of this study also show that the intensity of brain activation during knee movement can be influenced by the intensity of proprioceptive stimulation at the joint.

Muscle–tendon tissue properties in the hypermobility type of Ehlers‐Danlos syndrome

To investigate the passive properties of the plantar flexors muscle–tendon tissue in patients with the hypermobility type of Ehlers‐Danlos syndrome (EDS‐HT).